Using Hedonic Methods for Quality Adjustment in the CPI: The Consumer
Audio Products Component
Mary Kokoski, Keith Waehrer, and Patricia Rozaklis
Division of Price and Index Number Research
U.S. Bureau of Labor Statistics
2 Massachusetts Avenue, NE
Washington, DC 20212
This paper is a draft and a revised version will be published in the
future.
Abstract
There has been a strong recommendation that the BLS explore the use of hedonic
regression methods for quality adjustment in the Consumer Price Index (CPI). Until
recently data limitations have made this goal difficult to implement for many categories
of goods and services. This paper reports the preliminary results of employing data
purchased by BLS from an outside source to produce hedonic regression-based
quality-adjusted price indices for consumer audio electronics products. The effects of
hedonic-based quality adjustment are examined. Hedonic indices are derived directly from
the regression coefficients, and compared to the adjusted CPI values. Issues of regression
specification, and practical problems for CPI quality adjustment are also addressed.
I. Introduction
There has been strong recommendation that the BLS explore the use of hedonic methods
for quality adjustment in the Consumer Price Index (CPI) for decades. The Price Statistics
Review Committee (the Stigler Commission Report) in 1961 expressed the view that hedonic
analysis would provide a "more objective" approach to addressing quality change
than the BLS standard methods of dealing with this issue (Triplett (1990)). More recently,
the Advisory Commission to Study the Consumer Price Index (the Boskin Commission Report,
1996) reiterated this recommendation, recognizing that accurate measures of quality change
will enable a more accurate measure of pure price, or "cost-of-living" change.
Categories of goods and services where quality changes are frequent and relatively easy to
identify are the best candidates for using hedonic methods, given that data can be
acquired.
A price index, such as the CPI, intends to measure the effects of price changes while
holding other economic factors, such as the physical attributes of the goods available,
constant. In the real world, however, goods and services are always changing in their
physical characteristics. This makes it necessary to find some method of subtracting out
the value of quality change when the market basket and prices change. Traditionally, the
BLS has used several methods of quality adjustment. These include overlap pricing, direct
quality adjustment using information from producers, and linking methods. Basically, all
of these methods rely upon the subjective assessment of BLS personnel (commodity analysts)
in selecting newly appeared products that most closely match the disappearing ones.
Hedonic methods have been recently introduced into the BLS toolkit for housing (to correct
for age bias) and apparel commodities.
Research is underway which considers the use of hedonic methods for quality adjustment
for personal computers, televisions, VCRs, and even college textbooks, using or expanding
the CPI sample to estimate the hedonic regressions. In the CPI, the sample size for a
category of good or service is a function of the relative importance of that category in
the average consumer households total annual average expenditures. For many types of
goods and services where hedonic methods are likely to be useful, the sample of CPI data
is too small for such an empirical application. Possible solutions to this problem are to
collect additional observations on these goods for this purpose or to use supplementary
data sources to provide hedonic coefficient estimates that may be used for quality
adjustment when substitutions occur in the CPI sample.
For consumer audio products, the BLS is investigating the use of hedonic-based quality
adjustment methods from detailed and extensive market data acquired from NPD (Intelect
Group, Inc.). In this paper we present the preliminary results of this effort, examining
the effects of quality adjustment on this CPI component by comparing adjusted index values
to a simulated unadjusted CPI audio component. We discuss issues of regression
specification, practical problems encountered in integrating results from other data
sources into the CPI item structure, and also compare quality-adjusted results to a direct
hedonic index from the NPD regressions themselves.
II. Hedonics and Quality Adjustment in the CPI
Quality Adjustment in the CPI:
The purpose of a consumer price index is to measure the effects of price changes on
consumer households. In a true cost-of-living index, substitution behavior in response to
price changes is incorporated, and the index compares two price regimes with respect to a
fixed reference level of satisfaction. If a fixed weight formula, such as the Laspeyres,
is used for the index, relative prices of items are compared with respect to a fixed
market basket of goods and services. In either case, it is assumed that the spectrum of
products, and the available attributes of the goods or services from which the consumer
may choose are the same in both the reference and comparison periods.
In practice, however, the specific items on the market are often changing. Models
disappear and new, different ones appear to take their shelf space. Sometimes the
differences between old and new models are minor, or are regarded as such by the consumer.
Sometimes qualitative changes can occur which make the new products difficult to compare
to the old ones. At the extreme are goods which are sufficiently different from other
items on the market as to be categorized "new goods", since they embody
attributes, or specific combinations of attributes, which existing goods lack (e.g.
cellular telephones, and recordable portable minidiscs). These physical changes in
consumer products and services can be observed, but their value to the consumer must be
excluded from a consumer price index measure. Thus, they must be identified, categorized
and/or quanitified, and their implicit value to the consumer estimated.
The treatment of quality changes in the CPI has varied according to the nature and
degree of the change, feasible methods for making an adjustment, and available data
resources. Whether implicitly or explicitly, these adjustments attribute the observed
price change between two goods as: (a) entirely to price change, (b) entirely to quality
differences, or (c) partially to price change and the balance to quality difference
(Kokoski (1993)). Where the observed differences between a new and disappearing product
are negligible (e.g. brand of bran flake cereal), the price collector usually simply
substitutes the new product for the old one. This is termed a comparable substitution
and it implicitly attributes all of any observed price difference between the two products
to pure price change. Product "downsizing", as when 16-ounce cans of tomato
sauce are replaced by otherwise identical and similarly priced 14.5-ounce cans, also
attributes all of the difference in price-per-ounce to pure price change (Kokoski (1993)).
When qualitative attributes between two goods are judged to be more important, then one
of several methods of noncomparable substitution is employed. One such method, used
when both the old and new product are present in at least one time period, is overlap
pricing. In that overlap period, say period t, the price change for the item
category represented by these products is given by the price change for the old product
between period t-1 and period t. The price relative for this item category
between periods t+1 and t is represented by the new product. Empirically
seamless, this method does not require direct comparison of the prices or attributes of
the two products. It implicitly attributes all of any difference in price between the old
and new products to real quality difference. Where information is available on the
additional cost to producers of making a specific change in the attributes of a product,
then a direct quality adjustment may be made. This cost is then subtracted from any
observed change in the price paid by the consumer for the new instead of the old product
(Triplett (1988)). This direct method assumes that the perceived value of the quality
change to the consumer is the same as the cost incurred by the manufacturer to provide it.
In the absence of either overlapping prices or independent information from producers
on the costs of qualitative changes, a linking method is employed to make
noncomparable substitutions. Aside from sample rotations, when entirely new and
independent product samples are drawn for the CPI, linking techniques are the most
prevalently used in the CPI (Armknecht and Weyback (1989), Fixler (1993)). In this case
the old product makes its final appearance in period t-1 and the new product, which
effectively replaces it on the retail shelf, first appears in period t. Since the
two products cannot be directly compared in the same time period, the price change between
period t-1 and period t for this good is proxied by the observed price
change between these two periods by other goods in the same goods category. The new
product then represents the good in the price index for subsequent time periods. This
method assumes that pure price changes are likely to be the same for all goods in a class
(e.g. price changes for cotton Oxford shirts will be the same as for other types of
shirt). By implicitly imputing a price to the new product in period t-1, had it
existed then, this method attributes some of the price difference between the new and old
products to pure price change and the rest to quality differences between the two products
(Kokoski (1993)). All of the above methods would miss any pure price change imposed by the
producer at the opportunity offered by model changeovers.
In all these cases, some degree of judgment by the BLS commodity analyst is required.
For comparable substitutions, the analyst selects the new item which most closely
resembles the old one and judges any differences between them to be negligible. For
noncomparable substitution methods, the new item is still chosen on the basis of this
criterion, and then quantitative adjustments applied as the new item enters the index.
The currently preferred method of quality adjustment is the hedonic method. This
method (or class of methods (Triplett (1990)), relies on statistical techniques to
estimate the implicit prices of product characteristics from observed prices and
quantities sold in the marketplace. These implicit prices may then be used as measures of
the value of observable qualitative differences in products to consumers, and thus help
disaggregate the observed price difference between two products into quality change and
pure price change. The first application of hedonic methods to the CPI was in the apparel
categories (Armknecht (1984), Armknecht and Weyback (1989)). Initially, hedonic
regressions were estimated on the CPI sample, and the coefficient values for the
attributes used to provide a structured set of criteria for selecting the most comparable
substitute for a disappearing item. For example, if the fiber content of a jacket was
statistically significant and a quantitatively substantial attribute in determining the
jackets price, then the new jacket chosen for the CPI sample would have to have the
same fiber content as the old one. This procedure then advanced to using the hedonic
regressions to provide estimates of quality change directly into the index (Liegey (1993),
Armknecht, Moulton, and Stewart (1995)). For example, when a new jacket was brought into
the index to substitute for a disappeared one, its introductory price was quantitatively
adjusted based on the coefficients from the hedonic regression on that apparel category.
The use of hedonic regressions in apparel employed the data collected by BLS for the CPI,
and was facilitated by a fairly large sample, and relatively easily identified and
empirically manipulated characteristics information from the CPI checklists.
Hedonic methods are now being proposed for other categories of goods and services in
the CPI. These include personal computers, televisions, VCRs, refrigerators and other
major appliances, and even college textbooks. In some cases, a larger number of price
quotes is being collected to expand the sample and thus provide a sufficiently large
database for estimating hedonic regressions. Because expanding sample size is not a
costless endeavor, in other cases the BLS is considering the acquisition and use of data
sources outside the agency for this task. These include data purchased from A.C. Nielsen,
collected from electronic scanners in retail outlets, data gleaned from published sources
such as Consumers Digest (Liegey and Shepler (1998)), and data purchased from
independent firms which collect and process retail transactions information. For consumer
audio products, data are being purchased from NPD. While large and detailed, these other
data resources do present some additional issues for quality adjustment of the CPI: (a)
the samples are not collected under the same probability sampling procedures used for the
CPI sample, so the relative degree of representation of specific models in the respective
samples will differ, (b) the item definitions, categorization, and attributes identified
will differ, and c) the representative outlets from which the BLS collects price quotes
for the CPI differs from those sampled by other data sources, thus effecting the product
mix and prices.
Hedonic Methods for Quality Adjustment:
The concept of empirical hedonic analysis can be traced to the 1930s (Court (1939)),
and its application to price indices to a major work by Griliches (1961). Since then
theoretical foundations have been established, and debated, for the methodology and its
interpretation in economics. The theoretical basis is attributed to Rosen (1974), whose
model describes a market equilibrium in which consumers select goods on the basis of the
characteristics they embody, and implicit prices for these characteristics emerge which
represent the value placed on them by consumers. These implicit prices represent
equilibrium prices in characteristics space, tangency points between production isoquants
and consumer indifference curves in "implicit markets" for characteristics. A
large literature exists on the interpretation and empirical applications of hedonics, and
a useful summary of the basic concepts and issues are available in Triplett (1986),
(1988), (1990)).
At the most general level, the hedonic function describes the relationship between the
observed market prices of physically heterogeneous goods and the amount of various
characteristics which these goods embody. The hedonic hypothesis states that
"heterogeneous goods are aggregations of characteristics, and economic behavior
relates to the characteristics" (Triplett (1988), p. 630). For consumer price index
applications, it is the consumer side of the behavioral equation which is of most
interest. It is assumed that the consumer optimizes his consumption of characteristics by
choosing the good which is closest to his or her optimal bundle of characteristics, given
his or her budget constraint and the implicit prices of those characteristics. The
implications of this behavior depend on more explicit assumptions of the nature of the
relationship between goods and characteristics: there may or may not be a continuous
spectrum of goods varieties embodying various levels of various characteristics;
characteristics may or may not be amenable to "repackaging" by the consumer
(analogous to the separability problem in goods space) (Fisher and Shell (1972)); and, the
information supplied by the model does not necessarily inform about the function and
parameters of the demand function.
Nonetheless, there appears to be a consensus that empirical hedonic analysis does
provide meaningful information for inferring the value consumers place on quality changes,
and the estimates from hedonic regressions can be reliably used to make quality
adjustments to price indices (Triplett (1988), (1990)). This may be done in one of several
ways. First, one can identify a disappearing product and select a substitute, then make a
quality adjustment to the observed price of one or the other item to make them
statistically comparable in quality. These are "indirect methods". In one such
method, one would multiply the hedonically-derived implicit price of a characteristic by
the difference n the level of that characteristic between the old and new product. One
then subtracts this quality change value from any observed price difference between the
two products. Another such method is to impute the price of an item in a period before it
appeared on the market, using the hedonic coefficients and the observed characteristics of
the product at issue. This imputes a reservation price for the newly appeared good.
Alternatively, one could adopt a "direct method". Under this approach one
estimates a quality adjusted price index directly from the hedonic regression itself.
Along with the characteristics variables, one specifies time period dummy variables in the
hedonic regression; the coefficients on these time dummies are then interpreted as the
price differences between the specified period and the reference period net of changes in
the quality attributes of the goods available in each period (Triplett (1986). If the
relative weights of each characteristic, or the models embodying them, remain the same,
then these methods should, in principle, yield similar results. In practice, since the
direct method relies upon samples from different time periods, it is unclear how the
characteristics implicit values, and therefore the regression coefficients, may
change over time as the overall product market evolves.
Whichever method of hedonic quality adjustment is applied, there are several empirical
issues to be addressed. The issue most familiar in the hedonic literature is that of
choosing an appropriate functional form. Theory does not provide guidance on this issue
and much debate has been waged on it in the empirical context. Although other forms cannot
be ruled out a priori (see, for example, Arguea and Hsiao (1993)), the most
empirically convenient has not been demonstrated inferior in most applications, either.
This is the semi-logarithmic form, where the log of the goods price is regressed on
a linear specification of the characteristics, and time dummies where desired (Griliches
(1971), Triplett (1987)).
In the context of quality adjustment of intertemporal price indices, the stability of
the hedonic regression coefficients over time is an important concern. Hedonic regressions
are often estimated on a cross-section sample, and thus capture a snapshot of the market
at a point in time. As the varieties of goods available, and other factors change, the
relationship between the goods characteristics and their implicit prices may change
(i.e. shifting demand and supply curves in the implicit characteristics markets). Thus,
the hedonic coefficients from one empirical study may not provide reliable quality
adjustments for the index in future periods. Even in regression equations which include
time dummies, it may not be reasonable to assume that the coefficients on the
characteristics variables are constant over the whole sample. Edmonds (1985) found in his
study on housing that his hedonic model was stable, but this observation cannot be
generalized. Silver (1998) has identified as a potential source of price index bias
changes in the pricing strategies for existing models by companies as they begin to market
new ones. This effect could also be reflected in characteristics space, as companies
change the implicit prices offered for various attributes of the goods (for example,
wireless headphones might begin to replace the wired ones which are bundled in models of
portable stereos). If hedonic methods are used to adjust a price index, it is prudent to
estimate the model again periodically, and attempt an analysis of the conditions under
which the model coefficients change, and are thus likely to change in the future.
Other empirical issues relate to the quality and quantity of data available for
performing the hedonic analysis. Errors in measurement of characteristics variables can be
important (Epple (1987)). Especially in cases where data are acquired from other firms or
agencies, it is important to assess how these data are collected and the nature of any
averaging or imputation applied to them before using them to specify hedonic regressions
to be applied to independent samples such as the BLS data. It is important that
economically relevant characteristics information be provided by the data, so that the
regression specification is meaningful. Another important consideration is that these data
represent transactions, not list prices, since the former are the market prices which
reflect consumers preferences through their demand behavior. It is also likely that
for many durable goods categories, such as electronics products, few consumers pay full
list price and the relationship between list price and the average market retail price is
unknown. Another concern is the potential for selection bias in the outlet or product
sample, which may result from the methods used to collect the data (e.g. only outlets
which use electronic scanners) or package it (e.g. elimination of outliers, imputation of
missing values, substitutions among items).
III. Application to the Consumer Audio Products Sector
The Consumer Audio Products Market:
Consumer audio products comprise heterogeneous categories of durable goods. These range
from home stereo receivers, amplifiers, and loudspeakers to pocket-sized headphone
radio/cassette players. Individual products range in price from thousands of dollars to
less than twenty dollars. Because most consumer audio products are physically durable for
decades, technological obsolescence is the main reason for the consumer to replace or add
to his or her stock of these goods. Product innovations range from making portable radios
smaller and increasing the number of compact discs that can be accommodated by a CD player
to major upgrades such as the replacement of turntables by compact disc players. In many
respects, this class of products is not unlike personal computer goods. As with computer
hardware, the specifications which describe quality changes are usually easy to identify
and quantify (e.g. watts per channel, frequency range, size), and there are many brands,
models, and varieties of features on the market. These quantifiable aspects of the
consumer audio product category facilitate hedonic analysis.
The merging of video products and computers with audio products is occurring, as
evidenced by the market proliferation of home theatre systems, magnetically shielded
computer speakers, Internet radio, and compression algorithms which permit music and voice
to be downloaded digitally from the Internet. The Consumer Electronics Manufacturers
Association reports that consumers are seeking to complement their home theater systems
with high performance audio goods. As household penetration of home theater
systems increases, demand for high performance audio goods will rise, effecting product
quality and prices in the overall audio product market.
The consumer audio products market is an interesting candidate for hedonic analysis
also because of technological innovations that have recently occurred, but have yet to
penetrate the U.S. market. The MiniDisc, originally introduced as a digital replacement
for the analog cassette, offers the portability of a headphone cassette player, the sound
quality of a CD player (with less skipping), and the ability to make custom digital
recordings directly from CDs. At present, consumer satisfaction with analog cassettes and
the prevalence of CDs has left U.S. consumers disinterested in the new format. As digital
products gain consumer acceptance and more prerecorded music becomes available on
MiniDisc, consumer demand is likely to increase. As electronic products become digital,
more of these once distinct and separate products can begin to interact and communicate
with each other.
MiniDisc represents a new good, but one which combines attractive attributes of several
goods familiar to the consumer. These changes provide an opportunity to examine the
implications of new goods as they begin to affect the market. Is it possible, for example,
to predict the market price of a MiniDisc unit, based on the hedonic coefficients of its
attributes as embodied in other established products and other empirical information?
The audio products market is summarized in Figure 1, which shows the number of units
sold by product category from February 1997 through March 1999 based on the NPD data
(described in the next section). Figure 2 shows the relative proportion of consumption
devoted to each audio product category, averaged over the February 1997 through March 1999
period. Portable CD Players and headset stereos, part of the portable audio market, are
the largest selling items. Figure 2 suggests that shelf systems, which are similar to but
smaller than rack systems, are rising at the latters expense. This finding confirms
claims by the Consumer Electronics Manufacturers Association that consumers are moving
towards sleeker compact systems and away from large rack systems. Figure 3 shows the
average vintage of specific items in each category, or the average number of years that a
specific make and model is extant in the market, as of March 1999. These vintages do not
vary much by category.
The Data:
The data used in the hedonic regression analysis were purchased by the Bureau of Labor
Statistics from NPD, a private firm which specializes in the collection and packaging of
such market data for sale. These data were generated from point-of-sale observations in
various retail chain outlets and each observation represents the average price for a
specific product model over a bimonthly (before January 1998) or monthly (after January
1998) period for each of several classifications of retail outlet types called
"channels."
The NPD data consist of thirteen categories of products: CD players, portable radios,
solid state recorders, portable tape recorders, portable radio cassette players, stereo
headset, stereo headphones, receivers/amplifiers/tuners, cassette decks, home speakers,
one brand rack systems, and shelf systems. The channels represented in the data include
department stores, mass merchandisers, electronics specialty stores, and catalogue
showrooms. Each observation consists not only of an average price, but also includes
information on the physical attributes of each model and number of units sold. The BLS has
been purchasing these data since the February/March bimonthly installment in 1997, and,
for each such installment performing a preliminary analysis to check for errors or
inconsistencies, and correcting them where necessary. For the purposes of empirical
analysis over all these data installments, the monthly data were averaged to create
bimonthly periods of data for 1998-1999.
The price and quantity observations supplied by NPD are national estimates. NPD
receives data from a subset of all the outlets that sell consumer audio electronics
products. The unit sales reported by these chains are then extrapolated to reflect
national aggregate sales and expenditures. The extrapolation process is straightforward.
First, the chains within the sample are categorized into channels. Then, the chains within
each channel are assigned to cells depending on their total revenue and the number of
stores in the chain. Each chain is then assigned an adjustment factor corresponding to the
number of chains with similar size characteristics, nationally divided by the number of
chains with similar characteristics in the NPD sample. This adjustment factor is used as a
weight when aggregating chain level data on units sold and total expenditures. The average
price reported for each model is then calculated by dividing total expenditures on that
model by the total number of units of that model sold.
Although these data do not consist of individual retail transactions, they do represent
a much larger number of transactions and models of products than the BLS data. They also
include detailed characteristics information, as well as information on the first date
when each particular model appeared in the NPD sample. If the inaugural date of appearance
of a model is known, then these data could potentially provide quantitative information
that would help track price change over the life cycle of a model. Vintage information is
useful in ascertaining the introduction and proliferation of new technologies in the audio
products market.
Audio product data collected by the Bureau of Labor Statistics are classified in an
item stratum called "Audio Equipment: RA05." For each monthly index,
approximately 167 price quotes are used to construct the price index for item stratum
RA05. Data are further broken down into car audio equipment and non-car audio equipment. A
CPI checklist for the audio equipment item stratum is included as Appendix Figure 1.
Attribute data collected by the BLS are somewhat limited in scope and do not capture
important product characteristics such as product introduction date, buffer memory, and
recent technological advancements such as surround sound capabilities. Several variables
that appear on the checklist are difficult to use in the context of hedonic regression
analysis. These factors, as well as small sample size, prevented the use of CPI data in
hedonic regressions. Therefore, we used the NPD sample to obtain coefficient estimates to
quality adjust goods in the CPI sample.
Model Specification:
For the hedonic regressions, we estimate models of the log-linear form.
,
i indexes observations, is
the price of observation i, and are the vectors of characteristics and period dummy variables associated with
observation i. Finally, is
taken to be the effect of unobservables on log price, which are assumed to be independent
of . This model was estimated
separately for the thirteen categories of audio commodities defined by the NPD data, with
the vector of attributes specific to each category. We model the characteristics that are
continuous or near continuous nonlinearly by allowing them to have quadratic and sometimes
cubic effects on log price. Categorical characteristics are modeled using dummy variables.
While the characteristics variables include many of the important attributes of a given
product, there are additional attributes that are unobserved but may also affect a
consumer's valuation of the product. For instance, while we can control for whether or not
a portable CD player has a memory buffer, we have no information concerning the player's
size and weight. It is possible that newer models may have more valuable unobserved
features. We attempt to control for these by including a variable for the vintage of a
given model. The vintage variable is calculated as the difference in years between March
1999, and the year and month that the model first appeared in NPD's survey. Hence, the
lower the vintage the newer the product. To the extent that newer models have unobserved
but valuable features, inclusion of the vintage variable in the vector of characteristics will help to control for these quality
changes.
While it is conjectured that vintage helps to control for unobserved characteristics,
there is also the possibility that it is picking up some of the price change that would
otherwise be subsumed by the time period dummy variables. If manufacturers and/or
retailers use the introduction of a new model to adjust their pricing on a given set of
characteristics, then it is likely that the coefficient on vintage will reflect some of
those price changes. Thus, it could be debated whether or not the vintage should be
included in the hedonic regressions. To examine its effect on the model, the regression is
estimated with and without this dubious variable and the results compared.
To use these empirical results to quality adjust the simulated CPI, we first observe
those cases where a substitution has been made in the CPI sample. Where one product model
has replaced another in the CPI sample, we add to the old products price a value
equal to the coefficients on those quality attributes which differ between the two. Thus,
if the old product was an Aiwa with the same measured physical attributes as the new Sony
which replaces it, we add to the old products price the difference in coefficient
values between Sony and Aiwa brands.
The interpretation of the coefficients on the period dummy variables is often described
somewhat vaguely as a hedonic price index. They therefore provide direct hedonic price
indices from the NPD data, which can be compared to the results of quality adjusting the
(simulated) CPI for these goods. There are, obviously, differences in the two samples that
would cause the results from the two approaches to differ. In the NPD, the data are from
independent samples in multiple periods, rather than the CPI approach of tracking price
changes for an individual product on a specific outlet shelf. Not every product is priced
in every period in the NPD, and regression-based methods where a coefficient on the time
period dummy variable is being calculated do not require that the same good be observed in
the periods being compared. Therefore, regression or hedonic indices differ from standard
price indices not only in the fact that they can control for quality changes in goods over
time, but also in the fact that it is not necessary to exclude goods from the calculation
that appear only in the first or last period. To construct an hedonic index with similar
sample characteristics as the CPI, we estimate the hedonic regressions also on a subset of
the NPD data, the subset consisting of those product models present in all time periods
under study. These are "restricted sample" models. Unfortunately, while it would
have been interesting to compare direct hedonic index results from regressions on both the
NPD and CPI samples, the CPI sample sizes proved too small for this empirical procedure.
We also estimate hedonic indices using both unweighted least-squares and weighted
least-squares. For the weighted case, we use a good's average expenditure share over all
periods for which we observe sales as the weight for that good in every period that it
appears in the data. The hedonic indices calculated using this weighting scheme are meant
to be comparable to the Tornqvist, which is the geometric mean of price relatives with
average expenditure shares as weights.
Analysis and Results:
Tables 1-6 contain the results from the hedonic regressions for table CD players,
portable CD players, main stereo speakers, surround speakers, receivers, and shelf
systems. Aside from the characteristics variables listed on the tables, the regressions
also include dummy variables for manufacturer. Since this is an extensive list, the
coefficients on these brand name dummy variables are included in a separate table in the
Appendix (Table A.1). As is described in the previous section, the regressions are
estimated using unweighted and weighted least-squares methods, and also with the vintage
variable included and excluded. The time dummy variables are bimonthly because the earlier
installments of the NPD data were provided on this basis.
These model specifications restrict the coefficients on the characteristics variables
to be time invariant. To test the acceptability of this hypothesis, we also estimated
these models for the unrestricted case where all of the characteristics were allowed to
have a different effect in each time period. We tested the validity of the assumed
restriction, and found that, with a single exception, the hypothesis could not be
rejected. The single exception occurs in the weighted least-squares regressions for shelf
systems, the category which seems to be expanding most rapidly in sales volume among the
audio products. If the coefficients on characteristics are allowed to change over time,
then the coefficients on the time dummy variables only reflect the inflationary price
effects on models with the reference characteristics and the interpretation of
hedonic-based indices would be suspect. Thus the acceptance of time-invariance, generally,
is reassuring for our study.
In most cases the coefficient estimates reported in Tables 1-6 have the expected sign.
There are a few notable exceptions, however. For instance, in the case of receivers, the
presence of a Dolby prologic decoder has a statistically significant negative effect on
price, compared to the reference of no surround sound decoder, in the unweighted
regressions. This superficially unexpected result may follow from the observation that
some very high-end low-sales-volume models do not have surround sound decoders, while most
mid-level higher sales-volume models do. In the unweighted regression these high-end
receivers have a larger impact on the overall coefficient estimates. This may thus
represent an example of characteristics bundling, where particular attributes are found
only on products with other specific attributes. The prologic decoder may be providing a
proxy for middle-range quality products.
The coefficient estimates from these NPD regressions were then applied to make
quantitative quality adjustments to those cases in the CPI sample where one product was
substituted for another. Because the CPI is a Laspeyres index, and because vintage
information is unavailable for CPI sample items, the unweighted, vintage-excluded
regression model was used to supply the coefficient values. To arrive at the quality
adjustment factor, the differences in the exponentiated values of the coefficients for the
relevant dummy variables were added to the differences in the coefficient values for
continuous variables. For example, consider the case where the discontinued product is a
Pioneer 100-watt-per-channel receiver, with an observed price of $179.99 in its last
period of inclusion in the CPI. Its chosen replacement in the CPI sample was a Sony
500-watts-per-channel receiver, so that the quality-adjusted price is $214.57. The
reliability of the procedure depends on the degree to which the most relevant attributes
are captured empirically by the regressions and can also be identified for the products in
the CPI sample. In most cases, however, the price predicted by the regression model was a
very reasonable estimate of the observed price of the actual new product on its inaugural
period in the CPI sample (sometimes within a dollar or two). The only variable which could
not be used explicitly in the quality adjustment assessments was vintage, but, for those
few cases where the CPI model number matched the NPD model number (so we could be sure
they were identical products) we found that the vintage of the model chosen by the CPI
staff as a substitute was very close to that of its disappearing counterpart. Thus,
although perhaps not consciously, the CPI field representatives are selecting substitutes
of similar physical character by selecting those of a similar vintage.
The results of the quality adjustment are provided in Table 7. The first column reports
the replicated CPI for audio components as a combined category, as simulated by an
algorithm developed by the BLS to replicate the published CPI as closely as possible. Its
month-to-month changes are also reported, in the second column. The third column provides
the replicated CPI with the regression-derived hedonic quality adjustments included, and
its corresponding month-to-month changes. Interestingly, the quality adjusted index values
do not decrease as rapidly as the unadjusted ones. A similar pattern was found by Liegey
and Shepler (1999) for videocassette recorders (VCRs) in the CPI. This is a small sample,
with relatively few substitutions occurring, and the statistical significance of the index
values is unknown. However, as for VCRs but unlike cars and computers, there is no
model-year turnover pattern to audio products marketing. Innovations do not rapidly
supplant existing models, obsolescence is seldom a factor (at least for the time period of
our study. Also, the products chosen as substitutes are of similar vintage to the
disappearing ones, not the newest models on the market, so that the average vintage of the
CPI sample is probably older than that of the current market as represented by the NPD
data. Thus, quality adjusting the audio products component of the CPI would not be
expected to result in a more rapidly decreasing index.
As a benchmark for comparison, indices for the NPD-defined product categories were
calculated from the NPD data itself. These are reported in Table 8. The first five rows of
the table provide the standard indices for the bimonthly periods from February/March 1997
to February/March 1999 . These are calculated by matching average price observations over
time for the NPD models. As required by the index formulas, we only include models in the
calculation for which prices are reported in the reference and comparison periods. Since
we wish to compare these indices also to the hedonic indices from the regressions, we have
dropped observations from the NPD sample with incomplete characteristics information.
Because we have several time periods available for analysis, we calculated not only the
Laspeyres index, but also the Paasche, Fisher, geometric mean, and Tornqvist formulas.
These are all reported in the first set of rows of the table. By mathematical necessity,
the geometric mean values are uniformly less than the Laspeyres, and, as expected, the
Fisher falls between the Laspeyres and the Paasche index values. Unexpectedly, however,
the Laspeyres index is below the corresponding Paasche index for all but one category of
products. When price changes result only from changes in the supply side of the market one
would expect the substitution effects to result in the Laspeyres being lower than the
Paasche. That is not likely occurring in these data, but all of these categories do show a
substantial price decrease over a relatively short period. The Laspeyres indices for
portable CD players, receivers, and shelf systems indicate a decrease in price of more
than forty percent.
The next four rows of Table 8 report ordinary least-squares regression-based indices
for different samples and with the vintage variable included and excluded. The index value
is calculated as the exponentiated value of the estimated coefficient on the dummy
variable for the final period, times 100. The hedonic indices are calculated from the
results presented in Tables 1-6. In the restricted sample regression index, the
coefficient on the final time period dummy variable was estimated with no other covariates
and the same set of prices that were used in the calculation of the standard indices.
Therefore, the restricted sample regression includes no prices from periods other than the
first and last or from models without a price in either the first or last periods. Hence,
any difference between the restricted sample regression indices and the standard indices
is solely a result of the fact that the formula for the regression-based index differs
from that of the standard indices.
As with the standard price indices, the restricted sample only considers the price
effects of models in existence in the first and last periods; new models are considered
noncomparable to any models dropping out of the sample. Therefore, these indices will miss
changes in price associated with the introduction of a new model. For instance, a new
higher quality model might be introduced at a similar price as an older model and, hence,
should be registered as a (quality-adjusted) price decrease. On the other hand, the
introduction of a new model might be considered an opportunity to raise prices and hence,
represents a pure price increase. In Table 8, the regression index calculates a price
index from the coefficient on the final period time dummy estimated without any
characteristics covariates but on the same sample from which the hedonic indices are
estimated. The regression index also includes indicator variables for the other periods.
Hence, any difference between the restricted sample regression index and the regression
index is due to the fact that new models are included under the implicit assumption that
they are of the same quality as discontinued models. For the unweighted case, for all
categories, the (full sample) regression index is higher than the restricted sample
regression index. We interpret this result as implying that new models, not accounted for
in the restricted sample indices, are entering the market at prices higher than
discontinued or extant older models.
The hedonic indices are estimated on the same sample as the standard indices. However,
the hedonic regressions include the characteristics covariates, and thus are net of the
value of quality changes. In the unweighted case, when vintage is excluded, the hedonic
index values are higher than the standard index values. Hence, new models appear to be
entering the market with more highly valued characteristics. The hedonic index which
includes vintage is usually lower than the corresponding standard index. It is generally
lower than the hedonic index which excludes vintage, which supports the hypothesis that
vintage provides a "catch-all" variable for those quality improvements which are
not elsewhere specified in the regression. It does, however, appear that new higher
quality models are entering the market at higher quality adjusted prices. In general,
these comparisons among indices derived from the NPD sample alone corroborate the results
found for the CPI replication in Table 7, indicating that there is not an anomaly inherent
in the CPI sample.
Even when vintage is included in the hedonic regression the hedonic indices remain
generally above the standard regression index values. The relationships between the
various types of regression-based indices described above for the unweighted case also
hold for the weighted least-squares estimates. However, in general the weighted estimates
show a smaller price decline than the unweighted estimates. Note that, as expected, the
restricted sample regression indices are relatively close to the Tornqvist indices.
In Table 9 the direct hedonic indices are compared to the quality-adjusted CPI values
for the period 1998. The hedonic index with vintage excluded is derived from the same
regressions that supplied the coefficient values to adjust the CPI, and it is reassuring
that the two series are similar. In the last bimonthly period of this comparison, the
quality adjusted CPI appears to decrease less quickly than its direct hedonic
counterparts, although the statistical significance of these differences is unknown.
Contrary to a priori expectations, these empirical results indicate that hedonic
quality adjustment may produce higher index values as compared to the case where all new
goods are treated as noncomparable. This result seems to be consistent with the conjecture
that the introduction of new models is used as an opportunity to raise price. When new
models are treated as noncomparable, this price increase remains unaccounted for in the
index calculation. Given empirical studies on computers (Stavins (1997)) and television
sets in the U.K. (Silver (1998)) and others (Parker (1992)), this model changeover price
increase does appear to be a marketing strategy in practice. Not only can producers
"piggyback" a pure price increase on new models, it is also possible that the
subset of consumers which are most likely to purchase these new models (the
"innovators" (Parker (1992)) are less price-sensitive than other consumers and
are willing to pay a premium for the new product because it is new.
IV. Conclusions and Future Research Agenda
Hedonic analysis has long been recommended as a preferred method of quality adjustment
of the CPI. For many CPI components an hedonic approach will likely be adopted before the
next scheduled revision in 2002. This paper presents the preliminary results of employing
average price and quantity data from a private source to this end for consumer audio
electronics products. We have used the hedonic regression coefficients from these data to
supply quantitative estimates of quality differences for those situations when
substitutions were made in the CPI sample. Also, we have compared the resulting index
values to direct hedonic indices calculated from the time dummy variables in the hedonic
regressions.
Analysis of these results suggests several interesting empirical issues worthy of
further investigation. The quality adjusted indices indicate price decreases over the time
period under study, but less so than their unadjusted counterparts. The differences are
small, however, so it would be useful to continue empirical investigation, especially
during periods where physical changes to audio products are rapid and pronounced. The
regression specification with respect to characteristics variables appears to be stable
and consistent over time. Interestingly, among the direct hedonic formulas compared, we
observed that for all but one product category, the Laspeyres index value is below that of
the Paasche index. Altogether, these results support the proposition that new products may
be entering the sample at higher quality adjusted prices than those of extant models, an
issue that bears further investigation.
Future research will continue to focus on issues of regression specification.
Recognizing that the theoretical premise of the hedonic hypothesis is a comparative static
model, it is advisable to examine the behavior of characteristics implicit prices in the
dynamic market context. The importance of currently unobserved quality attributes in the
hedonic model merits more research, especially given that the vintage variable appeared to
be important to the numerical results.
References
Arguea, Nestor, and Cheng Hsiao (1993) "Econometric issues of estimating
hedonic price functions," Journal of Econometrics, 56, pp.243-267.
Armknecht, Paul (1984) "Quality Adjustment in the CPI and Methods to Improve
It," Proceedings of the Business and Economic Statistics Section, American
Statistical Association, pp. 57-63.
Armknecht, Paul, and Donald Weyback (1989) "Adjustments for Quality Change in the
U.S. Consumer Price Index, Journal of Official Statistics, 5, pp. 107-123.
Armknecht, Paul, Brent Moulton, and Kenneth Stewart (1995) "Improvements to the
Food at Home, Shelter, and Prescription Drug Indexes in the Consumer Price Index,"
BLS Working Paper No. 263.
Court, Andrew (1939) "Hedonic Price Indexes with Automobile Examples," in
General Motors Corp. The Dynamics of Automobile Demand, New York: General Motors
Corp., pp. 99-117.
Edmonds, Radcliffe (1985) "Some Evidence on the Intertemporal Stability of Hedonic
Price Functions," Land Economics, 61, pp. 445-451.
Epple, Dennis (1987) "Hedonic Prices and Implicit Markets: Estimating Demand and
Supply Functions for Differentiated Products," Journal of Political Economy,
95, November, pp. 59-80.
Fisher, F., and K. Shell (1972) The Economic Theory of Price Indices: Two Essays on
the Effects of Taste, Quality, and Technological Change. New York: Academic Press.
Fixler, Dennis (1993) "The Consumer Price Index: underlying concepts and
caveats," Monthly Labor Review, 116, December, pp. 3-12.
Griliches, Zvi (1971) Price Indexes and Quality Change: Studies in New Methods of
Measurement. Cambridge: Harvard University Press.
Kokoski, Mary (1993) "Quality adjustment of price indexes," Monthly Labor
Review, 116, December, pp. 34-46.
Kokoski, Mary, and Keith Waehrer (1998) "Hedonics and Quality Adjustment for Price
Indices for Consumer Electronics Products," draft presented to NBER Summer Institute
Conference on Price Indices, July.
Liegey, Paul (1993) "Adjusting Apparel Indexes in the CPI for Quality Differences,
in Foss, M., M. Manser, and A. Young (eds.) Price Measurements and Their Uses.
National Bureau of Economic Research Studies in Income and Wealth, 57, Chicago: University
of Chicago Press, pp. 209-226.
Liegey, Paul, and Nicole Shepler (1999) "Using Hedonic Methods to Quality Adjust
VCR Prices: Plucking a Piece of the US CPIs Low Hanging Fruit?" Monthly
Labor Review, forthcoming.
Moulton, Brent, Timothy Lafleur, and Karin Moses (1999) "Research on Improved
Quality Adjustment in the CPI: The Case of Televisions," Proceedings of the Fourth
Meeting of the International Working Group on Price Indices, U.S. Dept. of Labor,
January, pp. 77-79.
Parker, P. (1992) "Price Elasticity Dynamics Over the Adoption Life Cycle," Journal
of Marketing Research, August, pp. 358-367.
Rosen, Sherwin (1974) "Hedonic Prices and Hedonic Markets: Product Differentiation
in Pure Competition," Journal of Political Economy, April, pp. 34-55.
Silver, Mick (1998) "Bias in the Compilation of Consumer Price Indices when
Different Models of an Item Coexist," paper presented to the 1998 Ottawa Conference
at the U.S. Bureau of Labor Statistics, Washington, D.C, April.
Stavins, J. (1997) "Estimating Demand Elasticities in a Differentiated Product
Industry: The Personal Computer Market," Journal of Economics and Business,
49, pp. 347-367.
Triplett, Jack (1986) "The Economic Interpretation of Hedonic Methods," Survey
of Current Business, January, pp. 36-40.
Triplett, Jack (1988) "Hedonic functions and hedonic indexes," in The New
Palgraves Dictionary of Economics, pp. 630-634.
Triplett, Jack (1990) "Hedonic methods in statistical agency environments: an
intellectual biopsy," in Berndt, E.R., and J.E. Triplett (eds.) Fifty years of
economic measurement: the Jubilee Conference on Research in Income and Wealth, NBER
Studies in Income and Wealth, Chicago: University of Chicago Press.
Table 1: Table CD Players
|
|
Vintage
Included
Unweighted |
|
Vintage
Included
Weight: Average Expenditure Share |
|
Vintage
Excluded
Unweighted |
|
Vintage
Excluded
Weight: Average Expenditure Share |
|
|
Intercept |
5.5362
(0.1201) |
** |
5.5677
(0.1036) |
** |
5.0116
(0.1128) |
** |
5.1559
(0.0979) |
** |
Load Capacity |
|
|
|
|
|
|
|
|
|
|
CD Capacity |
-0.0447
(0.0055)
|
** |
-0.0282
(0.0053)
|
** |
-0.0472
(0.0059)
|
** |
-0.0231
(0.0054)
|
** |
|
CD Capacity, Squared |
0.0010
(0.0001)
|
** |
0.0007
(0.0001)
|
** |
0.0011
(0.0001)
|
** |
0.0006
(0.0001)
|
** |
Type of Loader Ref.:
Top Loader
|
|
|
|
|
|
|
|
|
|
|
Drawer Disc Loader |
0.1073
(0.0935)
|
|
0.1472
(0.0843)
|
* |
0.1588
(0.0994)
|
|
0.1424
(0.0864)
|
* |
|
Front Disc Loader |
0.3346
(0.0855)
|
** |
0.3035
(0.0811)
|
** |
0.5434
(0.0900)
|
** |
0.2189
(0.0827)
|
** |
Other Features |
|
|
|
|
|
|
|
|
|
|
Remote Control |
0.2875
(0.0283)
|
** |
0.1101
(0.0179)
|
** |
0.2577
(0.0300)
|
** |
0.1100
(0.0183)
|
** |
Time Period Ref.:
Feb/Mar 1997
|
|
|
|
|
|
|
|
|
|
|
Apr/May 1997 |
0.0168
(0.0474)
|
|
-0.0400
(0.0474)
|
|
0.0227
(0.0505)
|
|
-0.0309
(0.0485)
|
|
|
June/July 1997 |
-0.0543
(0.0465)
|
|
-0.0844
(0.0444)
|
* |
-0.0277
(0.0494)
|
|
-0.0667
(0.0453)
|
|
|
Aug/Sept 1997 |
-0.0609
(0.0470)
|
|
-0.0778
(0.0442)
|
* |
-0.0129
(0.0499)
|
|
-0.0591
(0.0451)
|
|
|
Oct/Nov 1997 |
-0.1313
(0.0477)
|
** |
-0.1304
(0.0436)
|
** |
-0.0645
(0.0505)
|
|
-0.1071
(0.0445)
|
** |
|
Dec 1997/Jan 1998 |
-0.1630
(0.0479)
|
** |
-0.1568
(0.0432)
|
** |
-0.0835
(0.0507)
|
* |
-0.1320
(0.0440)
|
** |
|
Feb/March 1998 |
-0.1773
(0.0487)
|
** |
-0.1818
(0.0427)
|
** |
-0.0813
(0.0514)
|
|
-0.1425
(0.0434)
|
** |
|
Apr/May 1998 |
-0.2060
(0.0497)
|
** |
-0.2187
(0.0425)
|
** |
-0.0881
(0.0523)
|
* |
-0.1729
(0.0431)
|
** |
|
June/July 1998 |
-0.2145
(0.0493)
|
** |
-0.2403
(0.0421)
|
** |
-0.0726
(0.0515)
|
|
-0.1807
(0.0425)
|
** |
|
Aug/Sept 1998 |
-0.2708
(0.0496)
|
** |
-0.2927
(0.0420)
|
** |
-0.1181
(0.0516)
|
** |
-0.2248
(0.0421)
|
** |
|
Oct/Nov 1998 |
-0.2837
(0.0514)
|
** |
-0.3288
(0.0421)
|
** |
-0.1106
(0.0533)
|
** |
-0.2563
(0.0422)
|
** |
|
Dec 1998/Jan 1999 |
-0.2893
(0.0511)
|
** |
-0.3508
(0.0419)
|
** |
-0.1169
(0.0529)
|
** |
-0.2656
(0.0418)
|
** |
|
Feb/March 1999 |
-0.3446
(0.0536)
|
** |
-0.3943
(0.0423)
|
** |
-0.1318
(0.0545)
|
** |
-0.2997
(0.0419)
|
** |
Model Vintage |
|
|
|
|
|
|
|
|
|
|
Vintage |
-0.0862
(0.0276)
|
** |
-0.2551
(0.0269)
|
** |
|
|
|
|
|
Vintage, Squared |
-0.0064
(0.0038)
|
* |
0.0390
(0.0049)
|
** |
|
|
|
|
Summary |
|
|
|
|
|
|
|
|
|
|
N |
2106 |
|
2106 |
|
2106 |
|
2106 |
|
|
R-squared |
0.4971 |
|
0.6108 |
|
0.4298 |
|
0.5908 |
|
|
Adjusted R-squared |
0.4848 |
|
0.6013 |
|
0.4165 |
|
0.5812 |
|
|
F-statistic |
40.618 |
** |
64.496 |
** |
32.307 |
** |
61.871 |
** |
Note: Numbers in parentheses
are standard errors.
** Significant at the 99 percent level.
* Significant at the 95 percent level. |
Table 2: Portable CD Players
|
|
Vintage
Included
Unweighted |
|
Vintage
Included
Weight: Average Expenditure Share |
|
Vintage
Excluded
Unweighted |
|
Vintage
Excluded
Weight: Average Expenditure Share |
|
|
Intercept |
4.8624
(0.0349)
|
** |
4.3974
(0.0303)
|
** |
4.3574
(0.0291)
|
** |
4.2109
(0.0257)
|
** |
Configuration
Ref.: CD Player Only |
|
|
|
|
|
|
|
|
|
|
Radio |
0.1981
(0.0401)
|
** |
0.2584
(0.0367)
|
** |
0.2733
(0.0426)
|
** |
0.3095
(0.0374)
|
** |
|
Radio and Cassette |
0.3362
(0.0153)
|
** |
0.3743
(0.0125)
|
** |
0.3395
(0.0162)
|
** |
0.3732
(0.0128)
|
** |
Load Capacity |
|
|
|
|
|
|
|
|
|
|
CD Capacity |
0.0839
(0.0180)
|
** |
0.1998
(0.0158)
|
** |
0.0424
(0.0190)
|
** |
0.1514
(0.0158)
|
** |
|
CD Capacity, Squared |
-0.0048
(0.0022)
|
** |
-0.0145
(0.0017)
|
** |
-0.0016
(0.0023)
|
|
-0.0106
(0.0017)
|
** |
|
CD Capacity, Cubed |
0.0000
(0.0000)
|
** |
0.0001
(0.0000)
|
** |
0.0000
(0.0000)
|
|
0.0001
(0.0000)
|
** |
Type of Loader Ref.:
Top Loader
|
|
|
|
|
|
|
|
|
|
|
Drawer Disc Loader |
0.1680
(0.0212)
|
** |
0.1230
(0.0186)
|
** |
0.1816
(0.0225)
|
** |
0.1308
(0.0190)
|
** |
|
Front Disc Loader |
0.0893
(0.0409)
|
** |
0.0813
(0.0401)
|
** |
0.1611
(0.0433)
|
** |
0.0942
(0.0410)
|
** |
Other Features |
|
|
|
|
|
|
|
|
|
|
Remote Control |
0.2540
(0.0115)
|
** |
0.2390
(0.0089)
|
** |
0.2955
(0.0121)
|
** |
0.2610
(0.0089)
|
** |
|
Buffer Memory |
0.2811
(0.0156)
|
** |
0.4213
(0.0142)
|
** |
0.3503
(0.0163)
|
** |
0.4389
(0.0144)
|
** |
|
Car Kit |
0.0179
(0.0149)
|
|
0.0549
(0.0123)
|
** |
-0.0115
(0.0158)
|
|
0.0470
(0.0125)
|
** |
Time Period Ref.:
Feb/Mar 1997
|
|
|
|
|
|
|
|
|
|
|
Apr/May 1997 |
0.0339
(0.0227)
|
|
-0.0688
(0.0236)
|
** |
0.0452
(0.0241)
|
* |
-0.0644
(0.0241)
|
** |
|
June/July 1997 |
-0.0406
(0.0225)
|
* |
-0.0776
(0.0229)
|
** |
-0.0154
(0.0239)
|
|
-0.0680
(0.0234)
|
** |
|
Aug/Sept 1997 |
-0.1337
(0.0223)
|
** |
-0.1265
(0.0226)
|
** |
-0.1030
(0.0236)
|
** |
-0.1141
(0.0231)
|
** |
|
Oct/Nov 1997 |
-0.1912
(0.0228)
|
** |
-0.1659
(0.0226)
|
** |
-0.1463
(0.0241)
|
** |
-0.1513
(0.0231)
|
** |
|
Dec 1997/Jan 1998 |
-0.2339
(0.0228)
|
** |
-0.1885
(0.0223)
|
** |
-0.1835
(0.0241)
|
** |
-0.1694
(0.0228)
|
** |
|
Feb/March 1998 |
-0.2899
(0.0231)
|
** |
-0.2557
(0.0218)
|
** |
-0.2266
(0.0244)
|
** |
-0.2256
(0.0222)
|
** |
|
Apr/May 1998 |
-0.3483
(0.0231)
|
** |
-0.2878
(0.0212)
|
** |
-0.2542
(0.0242)
|
** |
-0.2375
(0.0214)
|
** |
|
June/July 1998 |
-0.3704
(0.0229)
|
** |
-0.3161
(0.0210)
|
** |
-0.2578
(0.0239)
|
** |
-0.2565
(0.0211)
|
** |
|
Aug/Sept 1998 |
-0.4346
(0.0233)
|
** |
-0.3492
(0.0210)
|
** |
-0.3075
(0.0242)
|
** |
-0.2871
(0.0211)
|
** |
|
Oct/Nov 1998 |
-0.5320
(0.0242)
|
** |
-0.4238
(0.0210)
|
** |
-0.3853
(0.0250)
|
** |
-0.3594
(0.0211)
|
** |
|
Dec 1998/Jan 1999 |
-0.5067
(0.0241)
|
** |
-0.4242
(0.0210)
|
** |
-0.3600
(0.0250)
|
** |
-0.3580
(0.0210)
|
** |
|
Feb/March 1999 |
-0.5459
(0.0247)
|
** |
-0.4801
(0.0211)
|
** |
-0.3599
(0.0252)
|
** |
-0.4045
(0.0209)
|
** |
Model Vintage |
|
|
|
|
|
|
|
|
|
|
Vintage |
-0.2079
(0.0130)
|
** |
-0.1190
(0.0147)
|
** |
|
|
|
|
|
Vintage, Squared |
0.0176
(0.0018)
|
** |
0.0112
(0.0029)
|
** |
|
|
|
|
Summary |
|
|
|
|
|
|
|
|
|
|
N |
5351 |
|
5351 |
|
5351 |
|
5351 |
|
|
R-squared |
0.5279 |
|
0.6006 |
|
0.4659 |
|
0.5824 |
|
|
Adjusted R-squared |
0.5233 |
|
0.5968 |
|
0.4610 |
|
0.5786 |
|
|
F-statistic |
116.165 |
** |
156.243 |
** |
94.386 |
** |
150.898 |
** |
Note: Numbers in parentheses
are standard errors.
** Significant at the 99 percent level.
* Significant at the 95 percent level. |
Table 3: Main Stereo Speakers
|
|
Vintage
Included
Unweighted |
|
Vintage
Included
Weight: Average Expenditure Share |
|
Vintage
Excluded
Unweighted |
|
Vintage
Excluded
Weight: Average Expenditure Share |
|
|
Intercept |
3.8503
(0.1072)
|
** |
3.1454
(0.1040)
|
** |
3.5575
(0.1016)
|
** |
2.8831
(0.0996)
|
** |
Configuration
Ref.: Single Speaker |
|
|
|
|
|
|
|
|
|
|
Pair Configuration |
0.3292
(0.0253)
|
** |
0.3579
(0.0225)
|
** |
0.3213
(0.0257)
|
** |
0.3518
(0.0227)
|
** |
Power Ref.: Not
Powered
|
|
|
|
|
|
|
|
|
|
|
Powered |
0.4066
(0.0443)
|
** |
0.3611
(0.0298)
|
** |
0.4784
(0.0441)
|
** |
0.4168
(0.0292)
|
** |
Speaker Design Ref.:
Onwall Speaker
|
|
|
|
|
|
|
|
|
|
|
Shelf Speaker |
-0.2460
(0.0426)
|
** |
-0.0523
(0.0472)
|
|
-0.2216
(0.0434)
|
** |
-0.0378
(0.0475)
|
|
|
Floor Speaker |
0.0752
(0.0484)
|
|
0.3028
(0.0517)
|
** |
0.0747
(0.0493)
|
|
0.3086
(0.0521)
|
** |
|
Inwall Speaker |
-0.1526
(0.0430)
|
** |
0.0645
(0.0451)
|
|
-0.1336
(0.0438)
|
** |
0.0773
(0.0454)
|
* |
|
Other Speaker Design |
-0.0899
(0.1184)
|
|
0.0975
(0.0944)
|
|
-0.0835
(0.1206)
|
|
0.0859
(0.0952)
|
|
Speaker Crossover |
|
|
|
|
|
|
|
|
|
|
Main Speaker Crossover |
-0.0783
(0.0932)
|
|
-0.1112
(0.1571)
|
|
-0.0790
(0.0950)
|
|
-0.0515
(0.1583)
|
|
Woofer Size Ref.: Less
than 2 In.
|
|
|
|
|
|
|
|
|
|
|
4-8 Inch Woofer Size |
0.2780
(0.0563)
|
** |
0.6026
(0.0458)
|
** |
0.3101
(0.0573)
|
** |
0.6439
(0.0459)
|
** |
|
8-12 Inch Woofer Size |
0.4819
(0.0599)
|
** |
0.7619
(0.0487)
|
** |
0.5221
(0.0609)
|
** |
0.7996
(0.0489)
|
** |
|
Over 12 Inch Woofer Size |
0.6619
(0.0668)
|
** |
0.9855
(0.0543)
|
** |
0.7038
(0.0680)
|
** |
1.0031
(0.0548)
|
** |
Main Speaker Drivers Ref.:
One Driver
|
|
|
|
|
|
|
|
|
|
|
Two Drivers |
0.4833
(0.0845)
|
** |
0.5189
(0.1532)
|
** |
0.4734
(0.0862)
|
** |
0.5106
(0.1546)
|
** |
|
Three Drivers |
0.8009
(0.0867)
|
** |
0.8318
(0.1538)
|
** |
0.7846
(0.0884)
|
** |
0.8321
(0.1552)
|
** |
|
Four Drivers |
1.1207
(0.0909)
|
** |
1.2451
(0.1554)
|
** |
1.1235
(0.0926)
|
** |
1.2351
(0.1568)
|
** |
|
Five Drivers |
1.2599
(0.1079)
|
** |
1.2449
(0.1603)
|
** |
1.2161
(0.1099)
|
** |
1.2127
(0.1617)
|
** |
|
Six Drivers |
1.5551
(0.1206)
|
** |
1.6715
(0.1727)
|
** |
1.5005
(0.1228)
|
** |
1.6226
(0.1742)
|
** |
|
Seven Drivers |
1.6597
(0.1127)
|
** |
1.6700
(0.1619)
|
** |
1.5863
(0.1145)
|
** |
1.6111
(0.1632)
|
** |
Other Features |
|
|
|
|
|
|
|
|
|
|
Magnetic Shielding |
0.1178
(0.0206)
|
** |
0.1951
(0.0178)
|
** |
0.1667
(0.0205)
|
** |
0.2297
(0.0173)
|
** |
|
Weather Proofing |
0.1526
(0.0331)
|
** |
0.4212
(0.0276)
|
** |
0.1729
(0.0335)
|
** |
0.4072
(0.0277)
|
** |
|
Mounting Accessories |
-0.0845
(0.0297)
|
** |
-0.0412
(0.0298)
|
|
-0.0938
(0.0302)
|
** |
-0.0423
(0.0301)
|
|
|
Wireless |
0.3895
(0.1477)
|
** |
0.3884
(0.0880)
|
** |
0.3778
(0.1504)
|
** |
0.3358
(0.0886)
|
** |
Time Period Ref.:
Feb/Mar 1997
|
|
|
|
|
|
|
|
|
|
|
Apr/May 1997 |
-0.0224
(0.0331)
|
|
-0.0122
(0.0293)
|
|
-0.0192
(0.0337)
|
|
-0.0112
(0.0295)
|
|
|
June/July 1997 |
-0.0348
(0.0332)
|
|
-0.0273
(0.0291)
|
|
-0.0284
(0.0338)
|
|
-0.0251
(0.0294)
|
|
|
Aug/Sept 1997 |
-0.0445
(0.0330)
|
|
-0.0343
(0.0291)
|
|
-0.0337
(0.0337)
|
|
-0.0316
(0.0294)
|
|
|
Oct/Nov 1997 |
-0.0537
(0.0333)
|
|
-0.0340
(0.0283)
|
|
-0.0343
(0.0339)
|
|
-0.0245
(0.0286)
|
|
|
Dec 1997/Jan 1998 |
-0.0854
(0.0333)
|
** |
-0.0559
(0.0283)
|
** |
-0.0657
(0.0339)
|
|
-0.0440
(0.0284)
|
|
|
Feb/March 1998 |
-0.0864
(0.0332)
|
** |
-0.0643
(0.0279)
|
** |
-0.0583
(0.0338)
|
* |
-0.0466
(0.0279)
|
* |
|
Apr/May 1998 |
-0.0731
(0.0332)
|
** |
-0.0668
(0.0277)
|
** |
-0.0440
(0.0338)
|
|
-0.0411
(0.0277)
|
* |
|
June/July 1998 |
-0.0970
(0.0333)
|
** |
-0.0820
(0.0277)
|
** |
-0.0678
(0.0338)
|
** |
-0.0627
(0.0277)
|
** |
|
Aug/Sept 1998 |
-0.1142
(0.0336)
|
** |
-0.0959
(0.0278)
|
** |
-0.0791
(0.0341)
|
** |
-0.0748
(0.0278)
|
** |
|
Oct/Nov 1998 |
-0.1602
(0.0339)
|
** |
-0.1116
(0.0277)
|
** |
-0.1091
(0.0341)
|
** |
-0.0814
(0.0276)
|
** |
|
Dec 1998/Jan 1999 |
-0.1496
(0.0339)
|
** |
-0.1125
(0.0277)
|
** |
-0.0935
(0.0340)
|
** |
-0.0769
(0.0276)
|
** |
|
Feb/March 1999 |
-0.1344
(0.0352)
|
** |
-0.0999
(0.0281)
|
** |
-0.0655
(0.0349)
|
** |
-0.0604
(0.0279)
|
** |
Model Vintage |
|
|
|
|
|
|
|
|
|
|
Vintage |
-0.0583
(0.0136)
|
** |
-0.0875
(0.0108)
|
** |
|
|
|
|
|
Vintage, Squared |
-0.0004
(0.0014)
|
|
0.0071
(0.0010)
|
** |
|
|
|
|
Summary |
|
|
|
|
|
|
|
|
|
|
N |
3533 |
|
3533 |
|
3533 |
|
3533 |
|
|
R-squared |
0.8042 |
|
0.8726 |
|
0.7964 |
|
0.8701 |
|
|
Adjusted R-squared |
0.7996 |
|
0.8696 |
|
0.7918 |
|
0.8672 |
|
|
F-statistic |
174.988 |
** |
291.812 |
** |
170.993 |
** |
292.851 |
** |
Note: Numbers in parentheses are standard
errors.
** Significant at the 99 percent level.
* Significant at the 95 percent level. |
Table 4: Surround Speakers
|
|
Vintage
Included
Unweighted |
|
Vintage
Included
Weight: Average Expenditure Share |
|
Vintage
Excluded
Unweighted |
|
Vintage
Excluded
Weight: Average Expenditure Share |
|
|
Intercept |
4.9617
(0.1078)
|
** |
4.9842
(0.0853)
|
** |
4.5849
(0.0986)
|
** |
4.6897
(0.0749)
|
** |
Configuration Ref.:
Single Speaker
|
|
|
|
|
|
|
|
|
|
|
Pair Configuration |
0.4760
(0.1174)
|
** |
0.3969
(0.1105)
|
** |
0.4826
(0.1210)
|
** |
0.4356
(0.1115)
|
** |
|
Surround Configuration |
-0.1216
(0.0707)
|
* |
-0.3193
(0.0555)
|
** |
-0.0742
(0.0725)
|
|
-0.2193
(0.0543)
|
** |
Power Ref.: Not
Powered
|
|
|
|
|
|
|
|
|
|
|
Powered |
0.7032
(0.0491)
|
** |
0.4210
(0.0501)
|
** |
0.7854
(0.0501)
|
** |
0.5512
(0.0465)
|
** |
Speaker Type Ref.:
Main Speaker
|
|
|
|
|
|
|
|
|
|
|
Center Speaker |
-0.0461
(0.0548)
|
|
-0.3104
(0.0583)
|
** |
-0.0386
(0.0564)
|
|
-0.1997
(0.0565)
|
** |
|
Rear Speaker |
-0.6063
(0.1361)
|
** |
-0.2327
(0.1254)
|
* |
-0.5278
(0.1398)
|
** |
-0.1273
(0.1258)
|
|
System Type Ref.:
Three-Piece
|
|
|
|
|
|
|
|
|
|
|
Four-Piece System |
0.8569
(0.0896)
|
** |
1.0128
(0.0606)
|
** |
0.7054
(0.0914)
|
** |
0.8511
(0.0529)
|
** |
|
Five-Piece System |
0.7235
(0.1015)
|
** |
0.6145
(0.0727)
|
** |
0.7547
(0.1045)
|
** |
0.6526
(0.0733)
|
** |
|
Six-Piece System |
0.7727
(0.0714)
|
** |
1.0042
(0.0537)
|
** |
0.7921
(0.0735)
|
** |
0.9788
(0.0541)
|
** |
|
Other System |
1.7124
(0.1324)
|
** |
2.9632
(0.1029)
|
** |
1.5879
(0.1360)
|
** |
2.8468
(0.1026)
|
** |
Surround Speaker Ref.:
Other
|
|
|
|
|
|
|
|
|
|
|
Shelf Speaker |
0.2154
(0.0635)
|
** |
-0.1210
(0.0459)
|
** |
0.1299
(0.0648)
|
** |
-0.1379
(0.0447)
|
** |
|
Inwall Speaker |
1.9087
(0.4519)
|
** |
1.7953
(0.5576)
|
** |
2.0004
(0.4652)
|
** |
1.8716
(0.5636)
|
** |
|
Onwall Speaker |
0.1986
(0.0772)
|
** |
0.0123
(0.0750)
|
|
0.1511
(0.0793)
|
* |
-0.0027
(0.0756)
|
|
Other Features |
|
|
|
|
|
|
|
|
|
|
Magnetic Shielding |
0.0754
(0.0359)
|
** |
0.2009
(0.0302)
|
** |
0.1109
(0.0369)
|
** |
0.2073
(0.0305)
|
** |
|
Mounting Accessories |
0.0075
(0.0412)
|
|
-0.1897
(0.0323)
|
** |
0.0273
(0.0423)
|
|
-0.1738
(0.0316)
|
** |
|
THX Certification |
0.4154
(0.0540)
|
** |
0.3164
(0.0569)
|
** |
0.4578
(0.0555)
|
** |
0.3165
(0.0575)
|
** |
Time Period Ref.:
Feb/Mar 1997
|
|
|
|
|
|
|
|
|
|
|
Apr/May 1997 |
0.0021
(0.0443)
|
|
-0.0090
(0.0362)
|
|
0.0032
(0.0456)
|
|
-0.0084
(0.0366)
|
|
|
June/July 1997 |
-0.0868
(0.0439)
|
** |
-0.0434
(0.0357)
|
|
-0.0837
(0.0452)
|
* |
-0.0415
(0.0361)
|
|
|
Aug/Sept 1997 |
-0.0525
(0.0437)
|
|
-0.0499
(0.0354)
|
|
-0.0428
(0.0451)
|
|
-0.0471
(0.0358)
|
|
|
Oct/Nov 1997 |
-0.1113
(0.0439)
|
** |
-0.0909
(0.0347)
|
** |
-0.0936
(0.0452)
|
** |
-0.0822
(0.0351)
|
** |
|
Dec 1997/Jan 1998 |
-0.0826
(0.0447)
|
* |
-0.1027
(0.0346)
|
** |
-0.0596
(0.0460)
|
|
-0.0915
(0.0349)
|
** |
|
Feb/March 1998 |
-0.0926
(0.0451)
|
** |
-0.1200
(0.0343)
|
** |
-0.0534
(0.0464)
|
|
-0.1045
(0.0346)
|
** |
|
Apr/May 1998 |
-0.1207
(0.0458)
|
** |
-0.1099
(0.0345)
|
** |
-0.0836
(0.0471)
|
* |
-0.0949
(0.0348)
|
** |
|
June/July 1998 |
-0.1234
(0.0465)
|
** |
-0.1206
(0.0346)
|
** |
-0.0794
(0.0477)
|
* |
-0.1033
(0.0348)
|
** |
|
Aug/Sept 1998 |
-0.1092
(0.0459)
|
** |
-0.1420
(0.0336)
|
** |
-0.0525
(0.0469)
|
|
-0.1170
(0.0338)
|
** |
|
Oct/Nov 1998 |
-0.1791
(0.0466)
|
** |
-0.1620
(0.0336)
|
** |
-0.1059
(0.0473)
|
** |
-0.1261
(0.0335)
|
** |
|
Dec 1998/Jan 1999 |
-0.1927
(0.0465)
|
** |
-0.1854
(0.0336)
|
** |
-0.1091
(0.0470)
|
** |
-0.1471
(0.0334)
|
** |
|
Feb/March 1999 |
-0.2133
(0.0477)
|
** |
-0.2471
(0.0340)
|
** |
-0.1205
(0.0479)
|
** |
-0.2041
(0.0335)
|
** |
Model Vintage |
|
|
|
|
|
|
|
|
|
|
Vintage |
-0.0569
(0.0238)
|
** |
-0.0519
(0.0216)
|
** |
|
|
|
|
|
Vintage, Squared |
-0.0065
(0.0030)
|
** |
-0.0001
(0.0034)
|
|
|
|
|
|
Summary |
|
|
|
|
|
|
|
|
|
|
N |
2383 |
|
2383 |
|
2383 |
|
2383 |
|
|
R-squared |
0.7892 |
|
0.8511 |
|
0.7758 |
|
0.8477 |
|
|
Adjusted R-squared |
0.7823 |
|
0.8463 |
|
0.7687 |
|
0.8429 |
|
|
F-statistic |
115.126 |
** |
175.821 |
** |
109.436 |
** |
176.055 |
** |
Note: Numbers in parentheses are standard
errors.
** Significant at the 99 percent level.
* Significant at the 95 percent level. |
Table 5: Receivers
|
|
Vintage
Included
Unweighted |
|
Vintage
Included
Weight: Average Expenditure Share |
|
Vintage
Excluded
Unweighted |
|
Vintage
Excluded
Weight: Average Expenditure Share |
|
|
Intercept |
5.1194
(0.1210)
|
** |
5.8255
(0.1591)
|
** |
4.4494
(0.1293)
|
** |
5.5482
(0.1681)
|
** |
Watts Capability |
|
|
|
|
|
|
|
|
|
|
Watts per Channel |
0.0095
(0.0003)
|
** |
0.0093
(0.0003)
|
** |
0.0093
(0.0003)
|
** |
0.0084
(0.0003)
|
** |
Radio Tuner Ref.:
Analog Tuner
|
|
|
|
|
|
|
|
|
|
|
Digital Tuner |
0.1022
(0.0654)
|
|
-0.0787
(0.0419)
|
* |
0.0660
(0.0720)
|
|
-0.0811
(0.0440)
|
* |
Other Features |
|
|
|
|
|
|
|
|
|
|
Graphic Equalizer |
0.0082
(0.0491)
|
|
-0.0046
(0.0504)
|
|
0.0704
(0.0520)
|
|
0.1378
(0.0524)
|
** |
|
Remote Control |
0.0205
(0.0776)
|
|
-0.0448
(0.1417)
|
|
0.1929
(0.0847)
|
** |
0.1461
(0.1493)
|
|
|
Video Switching |
0.7612
(0.0489)
|
** |
0.2344
(0.0463)
|
** |
0.9201
(0.0533)
|
** |
0.2057
(0.0493)
|
** |
|
THX Certification |
0.7772
(0.0375)
|
** |
0.6118
(0.0357)
|
** |
0.7503
(0.0412)
|
** |
0.6011
(0.0379)
|
** |
Surround Decoder |
|
|
|
|
|
|
|
|
|
|
Dolby Pro Logic |
-0.6937
(0.0474)
|
** |
-0.8021
(0.0298)
|
** |
-0.8464
(0.0504)
|
** |
-0.9624
(0.0291)
|
** |
|
Dolby Digital |
0.0302
(0.0492)
|
|
-0.1074
(0.0291)
|
** |
0.0229
(0.0536)
|
|
-0.1830
(0.0292)
|
** |
Time Period Ref.:
Feb/Mar 1997
|
|
|
|
|
|
|
|
|
|
|
Apr/May 1997 |
-0.0358
(0.0334)
|
|
0.0145
(0.0410)
|
|
-0.0309
(0.0368)
|
|
0.0363
(0.0437)
|
|
|
June/July 1997 |
-0.1117
(0.0327)
|
** |
-0.0835
(0.0393)
|
** |
-0.0777
(0.0360)
|
** |
-0.0423
(0.0418)
|
|
|
Aug/Sept 1997 |
-0.1819
(0.0331)
|
** |
-0.1237
(0.0396)
|
** |
-0.1412
(0.0364)
|
** |
-0.0678
(0.0420)
|
|
|
Oct/Nov 1997 |
-0.1905
(0.0327)
|
** |
-0.1575
(0.0379)
|
** |
-0.1336
(0.0360)
|
** |
-0.1017
(0.0402)
|
** |
|
Dec 1997/Jan 1998 |
-0.2447
(0.0326)
|
** |
-0.1972
(0.0376)
|
** |
-0.1784
(0.0358)
|
** |
-0.1331
(0.0398)
|
** |
|
Feb/March 1998 |
-0.2570
(0.0328)
|
** |
-0.2437
(0.0371)
|
** |
-0.1738
(0.0360)
|
** |
-0.1675
(0.0392)
|
** |
|
Apr/May 1998 |
-0.3228
(0.0333)
|
** |
-0.3117
(0.0365)
|
** |
-0.2099
(0.0363)
|
** |
-0.2134
(0.0385)
|
** |
|
June/July 1998 |
-0.3513
(0.0326)
|
** |
-0.3350
(0.0362)
|
** |
-0.2327
(0.0354)
|
** |
-0.2261
(0.0380)
|
** |
|
Aug/Sept 1998 |
-0.4223
(0.0329)
|
** |
-0.4036
(0.0360)
|
** |
-0.2914
(0.0357)
|
** |
-0.2897
(0.0377)
|
** |
|
Oct/Nov 1998 |
-0.4938
(0.0333)
|
** |
-0.4784
(0.0357)
|
** |
-0.3343
(0.0359)
|
** |
-0.3462
(0.0372)
|
** |
|
Dec 1998/Jan 1999 |
-0.5317
(0.0338)
|
** |
-0.5108
(0.0357)
|
** |
-0.3594
(0.0362)
|
** |
-0.3725
(0.0371)
|
** |
|
Feb/March 1999 |
-0.6127
(0.0344)
|
** |
-0.5726
(0.0359)
|
** |
-0.4148
(0.0365)
|
** |
-0.4258
(0.0372)
|
** |
Model Vintage |
|
|
|
|
|
|
|
|
|
|
Vintage |
-0.1799
(0.0219)
|
** |
-0.1387
(0.0244)
|
** |
|
|
|
|
|
Vintage, Squared |
0.0083
(0.0035)
|
** |
0.0019
(0.0050)
|
|
|
|
|
|
Summary |
|
|
|
|
|
|
|
|
|
|
N |
2509 |
|
2509 |
|
2509 |
|
2509 |
|
|
R-squared |
0.7952 |
|
0.8454 |
|
0.7513 |
|
0.8244 |
|
|
Adjusted R-squared |
0.7914 |
|
0.8426 |
|
0.7470 |
|
0.8213 |
|
|
F-statistic |
212.494 |
** |
299.292 |
** |
173.182 |
** |
269.114 |
** |
Note: Numbers in parentheses
are standard errors.
** Significant at the 99 percent level.
* Significant at the 95 percent level. |
Table 6: Shelf Systems
|
|
Vintage
Included
Unweighted |
|
Vintage
Included
Weight: Average Expenditure Share |
|
Vintage
Excluded
Unweighted |
|
Vintage
Excluded
Weight: Average Expenditure Share |
|
|
Intercept |
6.1140
(0.0909) |
** |
6.2224
(0.0759) |
** |
5.4493
(0.0948) |
** |
5.8222
(0.0815) |
** |
Product Type Ref.:
Micro, One-Piece
|
|
|
|
|
|
|
|
|
|
|
Midi, One Piece |
-0.7935
(0.1720)
|
** |
-0.5108
(0.1180)
|
** |
-1.2770
(0.2005)
|
** |
-1.1415
(0.1297)
|
** |
|
Midi, With Cassette |
-0.4662
(0.0659)
|
** |
-0.3945
(0.0519)
|
** |
-0.6833
(0.0760)
|
** |
-0.6800
(0.0573)
|
** |
|
Midi, Two Pieces |
-0.3812
(0.0933)
|
** |
-0.2333
(0.1626)
|
|
-0.6626
(0.1076)
|
** |
-0.6418
(0.1877)
|
** |
|
Mini, One Piece |
-0.4901
(0.0777)
|
** |
-0.6183
(0.0537)
|
** |
-0.5589
(0.0913)
|
** |
-0.5514
(0.0623) |
** |
|
Mini, With Cassette |
-0.5708
(0.0568)
|
** |
-0.5162
(0.0435)
|
** |
-0.7144
(0.0655)
|
** |
-0.7378
(0.0483)
|
** |
|
Mini, Two Pieces |
-0.3462
(0.0624)
|
** |
-0.0993
(0.0663)
|
|
-0.7010
(0.0703)
|
** |
-0.7134
(0.0699)
|
** |
|
Mini, Three Pieces |
-0.6589
(0.1149)
|
** |
-0.6094
(0.0661)
|
** |
-0.8592
(0.1346)
|
** |
-0.8349
(0.0756)
|
** |
|
Micro, With Cassette |
-0.5092
(0.0598)
|
** |
-0.2457
(0.0425)
|
** |
-0.5129
(0.0686)
|
** |
-0.3638
(0.0467)
|
** |
|
Micro, Two Pieces |
-0.0197
(0.0960)
|
|
0.1736
(0.0655)
|
** |
0.0332
(0.1124)
|
|
0.1303
(0.0754)
|
* |
|
Micro, Separate Amp. |
0.7130
(0.1373)
|
** |
0.6619
(0.1201)
|
** |
0.2851
(0.1597)
|
* |
0.4282
(0.1391)
|
** |
Watts Capability |
|
|
|
|
|
|
|
|
|
|
Watts per Channel |
0.0001
(0.0002)
|
|
0.0003
(0.0002)
|
* |
0.0006
(0.0002)
|
** |
0.0007
(0.0002)
|
** |
Subwoofer System |
|
|
|
|
|
|
|
|
|
|
Subwoofer System |
0.1270
(0.0409)
|
** |
0.0143
(0.0248)
|
|
0.1897
(0.0475)
|
** |
0.1078
(0.0282)
|
** |
Cassette Deck Ref.:
Single Cassette
|
|
|
|
|
|
|
|
|
|
|
Double Cassette |
-0.1659
(0.0414)
|
** |
-0.1598
(0.0320)
|
** |
-0.2092
(0.0484)
|
** |
-0.0018
(0.0362)
|
|
CD Capacity |
|
|
|
|
|
|
|
|
|
|
CD Capacity |
0.0249
(0.0038)
|
** |
0.0281
(0.0041)
|
** |
0.0184
(0.0044)
|
** |
0.0376
(0.0047)
|
** |
|
CD Capacity, Squared |
-0.0003
(0.0001)
|
** |
-0.0005
(0.0001)
|
** |
-0.0002
(0.0001)
|
** |
-0.0007
(0.0001)
|
** |
Other Features |
|
|
|
|
|
|
|
|
|
|
Digital Signal Processing |
0.0989
(0.0412)
|
** |
-0.0663
(0.0343)
|
* |
0.1046
(0.0473)
|
** |
-0.1519
(0.0393)
|
** |
|
Remote Control |
0.0726
(0.0478)
|
|
0.0951
(0.0523)
|
* |
0.2443
(0.0551)
|
** |
0.2139
(0.0605)
|
** |
|
Surround Sound |
0.1146
(0.0285)
|
** |
0.0838
(0.0166)
|
** |
0.2835
(0.0321)
|
** |
0.0873
(0.0189)
|
** |
|
Woofer Size |
0.0598
(0.0110)
|
** |
0.0178
(0.0072)
|
** |
0.0467
(0.0129)
|
** |
-0.0086
(0.0082)
|
|
|
Dolby Surround Sound |
0.1661
(0.0356)
|
** |
0.1840
(0.0206)
|
** |
0.1419
(0.0418)
|
** |
0.2154
(0.0239)
|
** |
Speakers Ref.: 4-Way
Speakers
|
|
|
|
|
|
|
|
|
|
|
2-Way Speakers |
0.2321
(0.0356)
|
** |
0.2115
(0.0260)
|
** |
0.2200
(0.0418)
|
** |
0.2405
(0.sd0296)
|
** |
|
3-Way Speakers |
0.3154
(0.0382)
|
** |
0.4508
(0.0320)
|
** |
0.2811
(0.0446)
|
** |
0.5108
(0.0353)
|
** |
|
4-Way Speakers |
0.2996
(0.0740)
|
** |
0.6047
(0.0500)
|
** |
0.4144
(0.0866)
|
** |
0.5772
(0.0579)
|
** |
Time Period Ref.:
Feb/Mar 1997
|
|
|
|
|
|
|
|
|
|
|
Apr/May 1997 |
-0.0033
(0.0390)
|
|
-0.0293
(0.0323)
|
|
0.0028
(0.0459)
|
|
-0.0176
(0.0375)
|
|
|
June/July 1997 |
-0.0326
(0.0392)
|
|
-0.0823
(0.0305)
|
** |
0.0003
(0.0461)
|
|
-0.0445
(0.0354)
|
|
|
Aug/Sept 1997 |
-0.0722
(0.0390)
|
* |
-0.1159
(0.0306)
|
** |
-0.0240
(0.0458)
|
|
-0.0678
(0.0354)
|
* |
|
Oct/Nov 1997 |
-0.1759
(0.0406)
|
** |
-0.1769
(0.0329)
|
** |
-0.1071
(0.0476)
|
** |
-0.1246
(0.0381)
|
** |
|
Dec 1997/Jan 1998 |
-0.1449
(0.0405)
|
** |
-0.1939
(0.0320)
|
** |
-0.0653
(0.0475)
|
|
-0.1286
(0.0370)
|
** |
|
Feb/March 1998 |
-0.1287
(0.0417)
|
** |
-0.2267
(0.0320)
|
** |
-0.0215
(0.0487)
|
|
-0.1369
(0.0369)
|
** |
|
Apr/May 1998 |
-0.2376
(0.0421)
|
** |
-0.2621
(0.0314)
|
** |
-0.0968
(0.0490)
|
** |
-0.1684
(0.0361)
|
** |
|
June/July 1998 |
-0.3139
(0.0422)
|
** |
-0.3517
(0.0304)
|
** |
-0.1455
(0.0489)
|
** |
-0.2287
(0.0346)
|
** |
|
Aug/Sept 1998 |
-0.3256
(0.0428)
|
** |
-0.3412
(0.0301)
|
** |
-0.1273
(0.0492)
|
** |
-0.2038
(0.0340)
|
** |
|
Oct/Nov 1998 |
-0.3988
(0.0437)
|
** |
-0.3919
(0.0301)
|
** |
-0.1582
(0.0497)
|
** |
-0.2528
(0.0340)
|
** |
|
Dec 1998/Jan 1999 |
-0.4242
(0.0439)
|
** |
-0.4052
(0.0300)
|
** |
-0.1710
(0.0498)
|
** |
-0.2651
(0.0339)
|
** |
|
Feb/March 1999 |
-0.5121
(0.0452)
|
** |
-0.4878
(0.0303)
|
** |
-0.2283
(0.0506)
|
** |
-0.3359
(0.0339)
|
** |
Mode Model Vintage |
|
|
|
|
|
|
|
|
|
|
Vintage |
-0.2321
(0.0286)
|
** |
-0.1570
(0.0231)
|
** |
|
|
|
|
|
Vintage, Squared |
0.0083
(0.0042)
|
** |
-0.0035
(0.0046)
|
|
|
|
|
|
Summary |
|
|
|
|
|
|
|
|
|
|
N |
1427 |
|
1427 |
|
1427 |
|
1427 |
|
|
R-squared |
0.7993 |
|
0.9428 |
|
0.7221 |
|
0.9225 |
|
|
Adjusted R-squared |
0.7904 |
|
0.9402 |
|
0.7101 |
|
0.9192 |
|
|
F-statistic |
89.129 |
** |
368.539 |
** |
60.191 |
** |
275.931 |
** |
Note: Numbers in parentheses are standard
errors.
** Significant at the 99 percent level.
* Significant at the 95 percent level. |
Table 7: CPI Quality Adjusted by NPD Regression Coefficients
Period |
Published
Index |
Month-to-Month
Change |
Quality
Adjusted Index |
Month-to-Month
Change |
Number
of Quality Adjusted Quotes |
Number
of Price Quotes |
9712 |
100.00 |
—- |
100.00 |
—- |
—- |
—- |
9801 |
99.47 |
0.99 |
99.52 |
0.99 |
3 |
158 |
9802 |
98.34 |
0.99 |
98.95 |
0.99 |
2 |
140 |
9803 |
98.71 |
1.00 |
98.50 |
1.00 |
5 |
152 |
9804 |
98.29 |
1.00 |
98.38 |
1.00 |
4 |
166 |
9805 |
97.26 |
0.99 |
97.22 |
0.99 |
3 |
187 |
9806 |
96.31 |
0.99 |
96.29 |
0.99 |
2 |
165 |
9807 |
95.79 |
1.00 |
95.99 |
1.00 |
4 |
170 |
9808 |
95.22 |
0.99 |
95.47 |
1.00 |
2 |
167 |
9809 |
95.53 |
1.00 |
96.81 |
1.01 |
12 |
186 |
9810 |
95.22 |
1.00 |
96.57 |
1.00 |
9 |
164 |
9811 |
93.40 |
0.98 |
94.75 |
0.98 |
4 |
186 |
9812 |
92.62 |
0.99 |
94.03 |
0.99 |
2 |
171 |
Table 8
February/March 1997=100
Direct Hedonic Price Indices: February/March 1997 to Feb/March 1999
|
|
Table CD
Players |
Portable
CD Players |
Main
Stereo Speakers |
Surround
Speakers |
Receivers |
Shelf
Systems |
Standard Indices |
|
|
|
|
|
|
|
|
Laspeyres |
66.58 |
61.35 |
91.65 |
77.34 |
59.28 |
61.76 |
|
Paasche |
94.11 |
63.50 |
96.81 |
86.26 |
66.85 |
51.39 |
|
Geometric Mean |
64.00 |
57.92 |
89.82 |
74.40 |
57.32 |
59.52 |
|
Fisher |
79.16 |
62.41 |
94.19 |
81.68 |
62.95 |
56.34 |
|
Tornqvist |
66.45 |
59.57 |
92.61 |
77.57 |
57.78 |
58.81 |
Indices (Unweighted) |
|
|
|
|
|
|
|
|
Restricted Sample Regression Index (No Quality Adjustment)
|
68.11 |
58.73 |
87.60 |
78.44 |
57.13 |
59.28 |
|
Full Sample Regression Index (No Quality Adjustment)
|
98.67 |
75.40 |
109.44 |
112.16 |
89.40 |
101.70 |
|
Full Sample Hedonic Index, Vintage
Excluded |
87.65 |
69.77 |
93.66 |
88.65 |
66.05 |
79.59 |
|
Full Sample Hedonic Index, Vintage Included |
70.85 |
57.93 |
87.43 |
80.79 |
54.19 |
59.92 |
Indices with Average Expenditure Share
Weights |
|
|
|
|
|
|
|
|
Restricted Sample Regression Index (No Quality Adjustment)
|
67.98 |
62.95 |
92.47 |
75.87 |
59.32 |
63.98 |
|
Full Sample Regression Index (No Quality Adjustment)
|
73.44 |
69.04 |
95.71 |
97.57 |
91.96 |
42.83 |
|
Full Sample Hedonic Index, Vintage
Excluded |
74.11 |
66.73 |
94.13 |
81.54 |
65.32 |
71.47 |
|
Full Sample Hedonic Index, Vintage Included |
67.42 |
61.87 |
90.50 |
78.10 |
56.41 |
61.40 |
Table 9
Dec 1997/Jan 1998=100
Comparison of Quality Adjusted CPI to Direct Hedonic Indexes
|
Feb/March
1998 |
April/May
1998 |
June/July
1999 |
August/Sept
1998 |
Oct/Nov
1998 |
Dec
1998/Jan 1999 |
Full Sample Hedonic Index, Unweighted, Vintage
Excluded |
100.50 |
98.92 |
97.25 |
96.01 |
92.42 |
92.84 |
Full Sample Hedonic Index,
Unweighted, Vintage Included |
99.10 |
96.38 |
93.94 |
91.67 |
86.42 |
86.28 |
Quality Adjusted CPI |
98.72 |
97.80 |
96.14 |
96.14 |
95.66 |
94.03 |
Table A.1: Regression Coefficients for Brand Names
Unweighted Full Sample Regressions, Vintage Included
Reference Brand: SONY
|
Table CD
Players |
|
Portable
CD Players |
|
Main
Stereo Speakers |
|
Surround
Speakers |
|
Receivers |
|
Shelf
Systems |
|
Acoustic Research |
|
|
|
|
0.7508
(0.0650)
|
** |
0.5641
(0.1477)
|
** |
|
|
|
|
Adcom |
1.1927
(0.1489)
|
** |
|
|
|
|
|
|
|
|
|
|
ADS |
|
|
|
|
1.4482
(0.3935)
|
** |
|
|
|
|
|
|
Advent |
|
|
|
|
0.1885
(0.0541)
|
** |
-0.6076
(0.0975)
|
** |
|
|
|
|
Aiwa |
0.0469
(0.1342)
|
|
-0.1694
(0.0157)
|
** |
|
|
-0.7220
(0.1003)
|
** |
-0.2710
(0.0780)
|
** |
-0.2744
(0.0489) |
** |
Alaron |
|
|
-1.0536
(0.1453)
|
** |
|
|
|
|
|
|
|
|
Altec |
|
|
|
|
-0.3787
(0.0769)
|
** |
-0.4561
(0.1924)
|
** |
|
|
|
|
Audiovox |
|
|
-0.9704
(0.1624)
|
** |
0.0914
(0.1821)
|
|
-0.2482
(0.1275)
|
* |
|
|
|
|
B&K |
|
|
|
|
|
|
|
|
1.7436
(0.1014)
|
** |
|
|
B&W |
|
|
|
|
2.0149
(0.0516)
|
** |
1.2722
(0.0902)
|
** |
|
|
|
|
Bang and Olufsen |
0.9252
(0.4423)
|
** |
|
|
2.2397
(0.0797)
|
** |
|
|
|
|
|
|
BIC |
|
|
|
|
0.3313
(0.0892)
|
** |
0.0487
(0.1268)
|
|
|
|
|
|
Bose |
|
|
|
|
1.0727
(0.0595)
|
** |
0.5210
(0.0899)
|
** |
|
|
1.5171
(0.0887)
|
** |
Boston Acoustics |
|
|
|
|
0.9309
(0.0496)
|
** |
0.7110
(0.0818)
|
** |
|
|
|
|
California Audio |
0.8425
(0.1821)
|
** |
|
|
|
|
|
|
|
|
|
|
Canton |
|
|
|
|
|
|
1.0331
(0.2627)
|
** |
|
|
|
|
Carver |
0.6329
(0.1487)
|
** |
|
|
|
|
|
|
1.2044
(0.1829)
|
** |
|
|
Casio |
|
|
-0.3098
(0.0818)
|
** |
|
|
|
|
|
|
|
|
Celestion |
|
|
|
|
0.7307
(0.1145)
|
** |
0.0658
(0.1808)
|
|
|
|
|
|
Cerwin Vega |
|
|
|
|
0.4448
(0.0630)
|
** |
0.2531
(0.0895)
|
** |
|
|
|
|
Craig |
|
|
-0.5331
(0.0332)
|
** |
|
|
|
|
|
|
|
|
Definitive |
|
|
|
|
0.8991
(0.0620)
|
** |
1.1715
(0.0830)
|
** |
|
|
|
|
Denon |
0.3725
(0.0498)
|
** |
|
|
|
|
0.1276
(0.2628)
|
|
0.6034
(0.0271)
|
** |
0.6393
(0.0685)
|
** |
Emerson |
|
|
-0.4115
(0.0584)
|
** |
|
|
|
|
|
|
-0.4113
(0.2190)
|
* |
Energy |
|
|
|
|
1.3530
(0.0653)
|
** |
0.5303
(0.1054)
|
** |
|
|
|
|
Fisher |
-0.2727
(0.0621)
|
** |
-0.2010
(0.0221)
|
** |
-0.3248
(0.3931)
|
|
-1.1974
(0.3350)
|
** |
-0.4663
(0.0501)
|
** |
0.0311
(0.0552)
|
|
General Electric |
|
|
-0.8763
(0.3241)
|
** |
|
|
|
|
|
|
-1.0385
(0.0912)
|
** |
Granprix |
|
|
-0.4944
(0.0321)
|
** |
|
|
|
|
|
|
|
|
Harman Kardon |
0.1494
(0.0900)
|
* |
|
|
|
|
|
|
0.7291
(0.0360)
|
** |
0.7614
(0.1274)
|
** |
Infinity |
|
|
|
|
0.7500
(0.0476)
|
** |
0.3495
(0.0806)
|
** |
|
|
|
|
JBL |
|
|
|
|
0.4234
(0.0464)
|
** |
0.1692
(0.0760)
|
** |
|
|
0.3919
(0.0966)
|
** |
Jensen |
|
|
|
|
-0.5600
(0.1074)
|
** |
-1.1529
(0.1361)
|
** |
|
|
|
|
JVC |
-0.2796
(0.0406)
|
** |
-0.1040
(0.0167)
|
** |
|
|
-0.8700
(0.2309)
|
** |
-0.2842
(0.0270)
|
** |
0.0501
(0.0330)
|
|
Kash Gold |
|
|
0.2256
(0.0906)
|
** |
|
|
|
|
|
|
|
|
KEF |
|
|
|
|
1.4686
(0.0550)
|
** |
1.2250
(0.1057)
|
** |
|
|
|
|
Kenwood |
-0.2845
(0.0390)
|
** |
-0.2088
(0.0244)
|
** |
-0.0892
(0.0895)
|
|
-0.3060
(0.0918)
|
** |
-0.1896
(0.0248)
|
** |
-0.0046
(0.0477)
|
|
KLH |
|
|
|
|
-1.3279
(0.0766)
|
** |
-0.6245
(0.1465)
|
** |
|
|
|
|
Klipsch |
|
|
|
|
1.0142
(0.0478)
|
** |
0.5931
(0.0788)
|
** |
|
|
|
|
Koss |
|
|
-0.2621
(0.0302)
|
** |
|
|
|
|
|
|
-0.6589
(0.1041)
|
** |
Krell |
1.9713
(0.3207)
|
** |
|
|
|
|
|
|
|
|
|
|
Lenoxx |
|
|
-0.5120
(0.1327)
|
** |
|
|
|
|
|
|
|
|
M&K |
|
|
|
|
2.1508
(0.0914)
|
** |
1.3169
(0.0884)
|
** |
|
|
|
|
Magnavox |
-0.6827
(0.0823)
|
** |
-0.1995
(0.0182)
|
** |
|
|
-0.9045
(0.1559)
|
** |
-0.0722
(0.2186)
|
|
-0.2463
(0.0600)
|
** |
Marantz |
0.5306
(0.0715)
|
** |
|
|
|
|
|
|
0.7734
(0.0447)
|
** |
0.4586
(0.1580)
|
** |
Martin Logan |
|
|
|
|
2.7095
(0.0862)
|
** |
2.5872
(0.1247)
|
** |
|
|
|
|
McIntosh |
|
|
|
|
|
|
1.9685
(0.1519)
|
** |
|
|
|
|
Memorex |
|
|
-0.5250
(0.1233)
|
** |
|
|
|
|
|
|
|
|
Meridian |
3.0683
(0.2562)
|
** |
|
|
2.4800
(0.2044)
|
** |
2.6593
(0.1963)
|
** |
|
|
|
|
Mirage |
|
|
|
|
1.0915
(0.0593)
|
** |
0.8990
(0.0819)
|
** |
|
|
|
|
Mission |
|
|
|
|
0.6957
(0.0649)
|
** |
0.2228
(0.1454)
|
|
|
|
|
|
Mitsubishi |
0.1353
(0.1575)
|
|
|
|
1.1184
(0.2800)
|
** |
0.3366
(0.1007)
|
** |
0.4975
(0.0593)
|
** |
|
|
MTC |
0.4820
(0.4510)
|
|
|
|
|
|
|
|
|
|
|
|
MTX |
|
|
|
|
-0.0059
(0.0725)
|
|
-0.2111
(0.1503)
|
|
|
|
|
|
NAD |
0.4435
(0.0912)
|
** |
|
|
|
|
|
|
2.0082
(0.1713)
|
** |
|
|
Nakamichi |
1.1127
(0.1421)
|
** |
|
|
|
|
|
|
1.3945
(0.3102)
|
** |
|
|
Newtech |
|
|
-0.4925
(0.0717)
|
** |
|
|
|
|
|
|
|
|
NHT |
|
|
|
|
0.6946
(0.1311)
|
** |
0.5715
(0.2327)
|
** |
|
|
|
|
Niles |
|
|
|
|
0.9222
(0.0649)
|
** |
|
|
|
|
|
|
Onkyo |
0.1686
(0.0521)
|
** |
-0.2892
(0.1456)
|
** |
|
|
-0.1508
(0.1937)
|
|
0.3964
(0.0279)
|
** |
0.3867
(0.0726)
|
** |
Panasonic |
-0.3134
(0.1310)
|
** |
-0.1125
(0.0151)
|
** |
|
|
|
|
0.0709
(0.1396)
|
|
-0.0650
(0.0514)
|
|
Paradigm |
|
|
|
|
1.1263
(0.0882)
|
** |
0.9519
(0.1036)
|
** |
|
|
|
|
Phase Tech |
|
|
|
|
1.2382
(0.0999)
|
** |
0.4816
(0.1455)
|
** |
|
|
|
|
Philips |
0.4605
(0.1823)
|
** |
-0.5106
(0.1087)
|
** |
|
|
-0.8583
(0.4411)
|
* |
-0.1772
(0.1390)
|
|
|
|
Pioneer |
-0.0100
(0.0325)
|
|
0.3451
(0.7183)
|
|
-0.4989
(0.0597)
|
** |
-0.4578
(0.0842)
|
** |
-0.1502
(0.0217)
|
** |
0.0127
(0.0394)
|
|
Pioneer Electech |
|
|
|
|
1.9669
(0.3953)
|
** |
|
|
|
|
|
|
Polk |
|
|
|
|
0.8673
(0.0477)
|
** |
0.6994
(0.0783)
|
** |
|
|
|
|
Polyflame |
|
|
0.5786
(0.3240)
|
* |
|
|
|
|
|
|
|
|
RCA |
-0.7437
(0.0992)
|
** |
-0.3371
(0.0197)
|
** |
-0.6318
(0.2803)
|
** |
-0.8544
(0.1361)
|
** |
0.4453
(0.1730)
|
** |
-0.3915
(0.0445)
|
** |
Recoton |
|
|
|
|
0.3863
(0.1577)
|
** |
0.0473
(0.1413)
|
|
|
|
|
|
Rock Solid |
|
|
|
|
1.2410
(0.0802)
|
** |
|
|
|
|
|
|
Rockustics |
|
|
|
|
1.3197
(0.0867)
|
** |
|
|
|
|
|
|
Rotel |
0.8977
(0.1985)
|
** |
|
|
|
|
|
|
0.9466
(0.3118)
|
** |
|
|
Samsung |
|
|
|
|
|
|
|
|
|
|
-0.2611
(0.3083)
|
|
Sansui |
-0.8506
(0.4417)
|
* |
|
|
|
|
|
|
|
|
|
|
Sanyo |
|
|
-0.4158
(0.0288)
|
** |
|
|
|
|
|
|
0.2439
(0.1578)
|
|
Sharp |
|
|
-0.3144
(0.0305)
|
** |
|
|
|
|
|
|
-0.1845
(0.0468)
|
** |
Sherwood |
-0.5394
(0.4413)
|
|
|
|
|
|
|
|
-0.2942
(0.1553)
|
* |
|
|
Snell |
|
|
|
|
1.2873
(0.3940)
|
** |
|
|
|
|
|
|
Sonance |
|
|
|
|
0.9820
(0.0805)
|
** |
|
|
|
|
|
|
Soundesign |
|
|
|
|
|
|
|
|
|
|
-0.8593
(0.0625)
|
** |
Speakercraft |
|
|
|
|
0.5702
(0.2028)
|
** |
|
|
|
|
|
|
Stereostone |
|
|
|
|
0.2406
(0.1420)
|
* |
|
|
|
|
|
|
Sumiko |
|
|
|
|
2.5607
(0.0713)
|
** |
1.5772
(0.1347)
|
** |
|
|
|
|
Symphonics |
-0.8845
(0.1486)
|
** |
|
|
|
|
|
|
|
|
|
|
Teac |
-0.6129
(0.1991)
|
** |
|
|
|
|
|
|
|
|
|
|
Technics |
-0.2931
(0.0377)
|
** |
|
|
-0.2434
(0.0631)
|
** |
-0.4114
(0.0926)
|
** |
-0.2853
(0.0249)
|
** |
0.4320
(0.0662)
|
** |
Toshiba |
|
|
|
|
|
|
|
|
-0.0190
(0.3090)
|
|
|
|
Venturer |
|
|
-0.5422
(0.1628)
|
** |
|
|
|
|
|
|
|
|
Velodyne |
|
|
|
|
|
|
1.5598
(0.0885)
|
** |
|
|
|
|
Wilson |
|
|
-0.6885
(0.1502)
|
** |
|
|
|
|
|
|
|
|
Yamaha |
0.0287
(0.0429)
|
|
|
|
-0.5201
(0.0573)
|
** |
-0.3598
(0.0782)
|
** |
0.3824
(0.0236)
|
** |
0.5024
(0.0538)
|
** |
Zenith |
|
|
|
|
|
|
|
|
|
|
-0.1038
(0.1296)
|
|
Note: Numbers in parentheses
are standard errors.
** Significant at the 99 percent level.
* Significant at the 95 percent level. |
Appendix Figure 1
Entry Level Item Checklist Specification Elements for CPI Audio Component
U.S. Department of Labor
Bureau of Labor Statistics
Consumer Price Index - ELI Checklist
_________________________________________________________________________
Collection Period: __ __ __ __
Outlet Number: __ __ __ __ __ __ __
Quote Code: __ __ __
Arranging Code: __ __ __ __
___________________________________________________________________________________
ELI No./ title RA051
AUDIO COMPONENTS, RADIOS, TAPE RECORDERS/PLAYERS, OTHER
Cluster code 01
____________________________________________________________________________________
Item Availability: 1-AVAILABLE 2-ELI NOT SOLD 3-INIT INCOMPLETE
Purpose of Checklist: 1-INIT 2-INIT COMPL 3-SPEC CORR 4-SUB 5-REINIT 6-CHECK REV
CURRENT PERIOD
Price _ _ _ _ _ _ . _ _ _
SALES TAX Included: YES NO
Type of Price: REG SALE
____________________________________________________________________________________
YEAR-ROUND in-season: JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC
____________________________________________________________________________________
Respondent: Location:
____________________________________________________________________________________
Field Message:
____________________________________________________________________________________
CLUSTER 01 - RADIOS, PHONOGRAPHS AND TAPE RECORDERS/PLAYERS
TYPE
A1 Radio, tape recorder/player combination
A2 Radio, tape player Combination
A3 Radio
A4 Tape recorder/player
A5 Tape player
BRAND
B99 __________________
MODEL NUMBER
C99 _________________
STYLE
D1 Personal portable music system
D2 Portable (carry about)
D3 Table model
RADIO RECEIVING CAPABILITIES
E1 FM stereo
E2 FM monaural
F1 AM stereo
F2 AM monaural
G99 Short wave band(s) number,__________________
H1 Weather band
I1 TV band
J99 Other(s) __________________
NUMBER OF TAPE UNITS
K1 Single tape unit
K2 Dual tape unit
TYPE OF TAPE USED
M1 Standard cassette
M99 Other__________________
FEATURES
N1 Headphones included as standard equipment
P1 Clock radio, digital
P2 Clock radio, analog face
Q1 One tone control
Q2 Two tone controls
Q99 Other _______________
S1 Variable tone control(s)
S2 Switchable tone controls
T1 Built-in microphone(s)
T2 External microphone(s) included as standard equipment
U1 Local/DX switch
V99 Other__________________
W99 Other__________________
X99 Other__________________
POWER
AA1 AC, house current
AB1 DC, Rechargeable battery(ies)included as standard equipment
AB2 DC, nonrechargeable battery(ies)equipment included as standard
AB3 DC, battery(ies)—not included
AC99 Other, __________________
____________________________________________________________
Bureau of Labor Statistics
Consumer Price Index - ELI Checklist
___________________________________________________________________________________
ELI No./ title RA051
CLUSTER 02 - COMPONENTS AND OTHER SOUND EQUIPMENT
TYPE
A1 Individual component
A2 Component system put together by outlet or consumer
A3 Component system put together by manufacturer
A4 Compact systems
A5 Convertible home/portable component system
COMPONENT(S) SELECTED FOR PRICING (Reporting of a price is optional)
B1 Receiver ** C99 $______________________________
D1 Turntable ** E99 $______________________________
F1 Compact disk player (CD) ** G99 $______________________________
H1 Tape deck ** I99 $______________________________
J1 Tuner ** K99 $______________________________
L1 Integrated amplifier ** M99 $______________________________
N1 Preamplifier ** P99 $______________________________
Q1 Power amplifier ** R99 $______________________________
S99 Speaker(s), Number___________ ** T99 $______________________________
U1 Casceiver ** V99 $______________________________
W1 Equalizer ** X99 $______________________________
Y1 Headphones ** AA99 $______________________________
AB1 Phono cartridge (only priced with turntable) ** AC99
$______________________________
AD99 Other component, _______________** AE99 $______________________________
AF99 Other component, ____________ ** AG99 $______________________________
AH1 Audio component rack ** AI99 $______________________________
AJ99 Other equipment,__________** AK99 $______________________________
AL99 Other equipment, ** __________AM99 $______________________________
AN99 Other equipment,_____________** AP99 $______________________________
BRAND, LINE AND MODEL NUMBER OF A3 OR A5
AX99 _____________________________
BRAND AND MODEL NUMBER OF COMPACT SYSTEM - A4
AY99 _____________________________
Casceiver - Use the specifications for receivers and tape decks for reporting
Compact system - Use the specifications for receivers, turntables, speakers and
if applicable tape decks for reporting.
—————————————————————————————————————————————————————————————————————-
RECEIVER
BRAND
BA99 ________________________ P>
MODEL NUMBER
BB99 ________________________
RECEIVING CAPABILITIES
BC1 FM stereo
BD1 AM stereo
BD2 AM monaural
BE99 Other bands ___________________
.>WATTAGE
BG99 __________________ /Channel
REMOTE CONTROL
BH1 Not available
BH2 Standard
BH3 Optional and not included
BH4 Optional and included
TURNTABLE
BRAND
CA99 _____________________________
MODEL NUMBER
CB99 ______________________________
CAPABILITIES
CC1 Single play (only one record)
CC2 Multiplay changer
OPTIONAL PHONO CARTRIDGE
CD1 Cartridge not included
CD2 Cartridge included by dealer
CD3 Cartridge included by manufacturer
BRAND AND MODEL OF PHONO CARTRIDGE
CE99 ______________________________
REMOTE CONTROL
CF1 Not available
CF2 Standard
CF3 Optional and not included
CF4 Optional and included
—————————————————————————————————————————————————————————————————————-
COMPACT DISC PLAYER
BRAND
CH99 ________________________
MODEL NUMBER
CI99 _________________________ ______________________________
CAPABILITIES
CJ1 Single disc
CJ99 Multidisc changer, # of discs _________________________
TYPE OF LASER PICK-UP
CK1 Three Beam
CK2 One beam
CK99 Other ___________________
PROGRAMMABILITY
CL99 Random access programmability, number of tracks programmable
CM99 Continuous playback of selected track, number of times __________________________
CN1 Continuous playback of entire disc
FEATURES
CP1 Music scan
CQ99 Other ____________________
CR99 Other _____________________
CS99 Other _____________________
REMOTE CONTROL
CT1 Not available
CT2 Standard WATTAGE
CT3 Optional and not included
CT4 Optional and included
TAPE DECK
BRAND
TYPE
DA1 Cassette (compact cassette)
DA2 DAT (Digital Audio Tape)
DA3 Reel-to-reel
DA99 Other ___________
DB99 ______________________________
DC99 ______________________________
NOISE REDUCTION SYSTEM
DG1 Dolby B
DH1 Dolby C system
DI1 DBX II system
DJ99 Other, system
CAPABILITIES
DK1 Single cassette
DK2 Dual cassette
REMOTE CONTROL
DL1 Remote control not available
DL2 Remote control standard
FEATURES
DL3 Remote control optional and not included
DL4 Remote control optional and included
INTEGRATED AMPLIFIER
BRAND
FA99 ______________________________
MODEL NUMBER
REMOTE CONTROL
FB99 ______________________________
FC99 __________________ RMS/Channel
REMOTE CONTROL
FD1 Remote control not available
FD2 Remote control standard
FD3 Remote control optional and not included
FD4 Remote control optional and included
————————————————————————————————————————————————————————————————————
PREAMPLIFIER
BRAND
GA99 _____________________
MODEL NUMBER
GB99 _____________________
REMOTE CONTROL
GC1 Remote control not available
GC2 Remote control standard
GC3 Remote control optional and not included
GC4 Remote control optional and included
POWER AMPLIFIER
BRAND
HA99 ______________________________
MODEL NUMBER
HB99 ______________________________
AMPLIFICATION
HC1 Stereo only
HC2 Stereo and monaural
HC3 Monaural only
HC99 Other __________________________
WATTAGE
HE99 __________________ RMS/Channel
SPEAKERS
BRAND
IA99 ______________________________
MODEL NUMBER
IB99 ______________________________
REPRODUCTION
IC1 Two way sound
IC2 Three way sound
IC99 Other _________________________
WOOFER SIZE (if stated)
ID1 6 inch
IE1 8 inch
IF1 10 inch
IG1 12 inch
IH99 Other,_________________________
EQUALIZER
BRAND
JA99 ______________________
MODEL NUMBER
JB99 _______________________
TYPE
JC1 Graphic
JC2 Parametric
JC99 Other __________________
NUMBER OF BANDS
JD98 _______________________
JD99 ______________________
HEADPHONES
BRAND
JG99 ________________________
MODEL NUMBER
JH99 ________________________
AUDIO COMPONENT RACK
BRAND
KA99 ________________________
MODEL NUMBER
KB99 _______________________
SIZE
KC99 Width __________________
KD99 Height __________________
KE99 Depth __________________
MAIN CONSTRUCTION MATERIAL
KF1 Wood
KF2 Metal
KF99 Other ___________________
KG1 Without doors
KG2 With doors
KH99 Door material_________________________
OTHER COMPONENTS AND/OR EQUIPMENT
TYPE LA99 _________________________________________
BRAND LB99 _________________________________________
MODEL NUMBER
LC99 _________________________________________
OTHER COMPONENTS AND/OR EQUIPMENT
_________________________________
TYPE MA99 _________________________________________
BRAND MB99 _________________________________________
MODEL NUMBER
MC99 _________________________________________
The following section may be completed for any item priced.
** ADDITIONAL AND CLARIFYING DATA
NA99 ______________________________________________
NB99 ______________________________________________
NC99 ______________________________________________
Last Modified Date: October 16, 2001