Chapter 16.
Consumer Expenditures and Income
The Current Survey
The need for more timely data than could be supplied by surveys
conducted every 10 to 12 years, intensified by the rapidly
changing economic conditions of the 1970s, led to the initiation
of the current continuing survey in late 1979. Since then,
data have been available annually. The objectives of the survey
remain the same: to provide the basis for revising the weights and
associated pricing samples for the CPI and to meet the need for
timely and detailed information on the spending patterns of
different types of families.
Like the 1972-73 survey, the current survey consists of two
separate surveys, each with a different data collection technique
and sample. In the Interview Survey, each family in the sample is
interviewed every 3 months over five calendar quarters. The sample
for each quarter is divided into three panels, with consumer units
being interviewed every 3 months in the same panel of every quarter.
The Diary (or recordkeeping) Survey is completed at home by the
respondent family for two consecutive 1-week periods.
The sample housing unit is notified in advance by a letter informing
the occupants about the purpose of the survey and the upcoming visit
by the interviewer. Both the Interview and the Diary Survey are conducted
primarily by personal visits with some telephone usage. The interviewer
uses a structured questionnaire to collect both the demographic and
expenditure data in the Interview Survey. The demographic data in the
Diary Survey are collected by the interviewer, whereas the expenditure
data are entered on the diary form by the respondent. If, after attempts
to contact the household, no adult is available, both surveys accept
responses from any eligible household member who is at least 16 years
old.
The unit for which expenditure reports are collected is the set
of eligible individuals constituting a consumer unit, which is
defined as (1) all members of a particular housing unit who are
related by blood, marriage, adoption, or some other legal
arrangement, such as foster children; (2) a person living alone
or sharing a household with others, or living as a roomer in a
private home, lodging house, or in permanent living quarters in
a hotel or motel, but who is financially independent; or (3) two
or more unrelated persons living together who pool their income
to make joint expenditure decisions. Students living in
university-sponsored housing are also included in the sample as
separate consumer units.
Survey participants report dollar amounts for goods and services
purchased during the reporting period whether payment was or was not
made at the time of purchase. The expenditure amounts include all
sales and excise taxes for all items purchased by the consumer unit
for itself or for others. Excluded from both surveys are all
business-related expenditures and expenditures for which the family
is reimbursed.
The Interview Survey collects detailed data on an estimated 60 to
70 percent of total family expenditures. In addition, global
estimatesthat is, estimated average expenditures for a 3-month
periodare obtained for food and other selected items. These global
estimates account for an additional 20 to 25 percent of total
expenditures. On the average, it takes approximately 65 minutes to
complete the interview.
In the Diary Survey, detailed data are collected on all
expenditures made by consumer units during their participation
in the survey. It is estimated that it takes approximately 25
minutes over three visits for the interviewer to collect the
demographic data and to instruct the respondent on how to keep
the diary. It is also estimated that it takes the respondent
about 12 minutes each day to complete the diary.
Quality control is provided by a reinterview program, which
constitutes a means of evaluating the performance of the individual
interviewer to determine how well the procedures are being carried
out in the field. The reinterview is conducted by a member of the
supervisory staff. A subsample of approximately 8 percent of
households in the Interview Survey and 11 percent in the Diary
Survey is reinterviewed on an ongoing basis.
All data collected in both surveys are subject to Census Bureau
and BLS confidentiality requirements that prevent the disclosure of
the respondents identities. All employees have taken an oath to
that effect.
Interview survey
The Interview Survey is designed to collect data on the types of
expenditures respondents can be expected to recall for a period of
3 months or longer. In general, expenditures reported in the Interview
Survey are either relatively large, such as for property, automobiles,
or major appliances, or occur on a fairly regular basis, such as for rent,
utility bills, or insurance premiums.
Each occupied sample unit is interviewed once per quarter for five
consecutive quarters. After the fifth interview, the sample unit is
dropped from the survey and replaced by a new sample unit. For the
survey as a whole, 20 percent of the sample is replaced each quarter.
New families are introduced into the sample on a regular basis as
other families complete their participation. Data collected in each
quarter are considered independently, so that estimates are not
dependent upon a family participating in the survey for a full five
quarters.
For the initial interview, information is collected on demographic
and family characteristics and on the inventory of major durable goods
of each consumer unit. Expenditure information is also collected in
this interview, using a 1-month recall, but is used, along with the
inventory information, solely for bounding purposes, that is, to
classify the unit for analysis and to prevent duplicate reporting of
expenditures in subsequent interviews.
The second through fifth interviews use uniform questionnaires to
collect expenditure information in each quarter. Data collected in these
questionnaires, which are arranged by major expenditure component
(for example, housing, transportation, healthcare, and education),
form the basis of the expenditure estimates derived from the Interview
Survey. Wage, salary, and other information on the employment of each
member of a consumer unit is also collected or updated during each of
these interviews. The expenditure data are collected via two major types
of questions. The first set of questions asks the consumer unit member for
the month of purchase directly for each reported expenditure. The
second asks for a quarterly amount of expenditures. The use of these
two types of questions varies, depending on the types of expenditures
collected. Approximately 65 percent of the data are collected using the
direct monthly method, whereas about 35 percent are collected with the
quarterly recall approach.
In the fifth and final interview, an annual supplement is used to
obtain a financial profile of the consumer unit. This profile consists
of information on the income of the consumer unit as a whole,
including unemployment compensation; income from royalties,
dividends, and estates; alimony and child support; and so forth.
A 12-month recall period is used to collect income- and asset-type
data.
Diary survey
The primary objective of the Diary Survey is to obtain expenditure
data on small, frequently purchased items, which are normally difficult
to recall. These items include food and beverage expenditures, at
home and in eating places; housekeeping supplies and services;
nonprescription drugs; and personal care products and services.
The Diary Survey is not limited to these types of expenditures,
but, rather, includes all expenses that the consumer unit incurs
during the survey week. Expenses incurred by family members while
away from home overnight and for credit and installment plan
payments are excluded.
Two separate questionnaires are used to collect Diary data: a
Household Characteristics Questionnaire and a Record of Daily
Expenses. In the Household Characteristics Questionnaire, the
interviewer records information pertaining to age, sex, race,
marital status, and family composition, as well as information on
the work experience and earnings of each member of the consumer
unit. This socioeconomic information is used by the Bureau to
classify the consumer unit for publication of statistical tables
and for economic analysis. Data on household characteristics also
provide the link in the integration of Diary expenditure data
with Interview expenditure data that permits the publication of
a full profile of consumer expenditures by demographic
characteristics.
The daily expense record is designed as a self-reporting,
product-oriented diary on which respondents record a detailed
description of all expenses for two consecutive 1-week periods.
Data collected each week are considered independently. The diary
is divided by day of purchase and by four classifications of goods
and servicesfood away from home, food at home, clothing, and all
other goods and servicesa breakdown designed to aid the respondent
in recording the entire consumer units daily purchases. The items
reported are subsequently coded by the Census Bureau so that BLS
can aggregate individual purchases for representation in the CPI
and for presentation in statistical tables.
Integrated survey data
The integrated data from the BLS Diary and Interview Surveys provide
a complete accounting of consumer expenditures and income, which
neither survey component alone is designed to do. Some expenditure
items are collected only by either the Diary or Interview Survey.
For example, the Diary collects data on detailed food expenditures
and items such as postage and nonprescription drugs, which are not
collected in the Interview. The Interview collects data on
expenditures for overnight travel and information on reimbursements,
such as for medical-care costs or automobile repairs, which are not
collected in the Diary. Data on average annual expenditures that come
exclusively from the Interview Survey, including global estimates such
as those for food and alcoholic beverages, average about 95 percent of
the total estimated spending, based on integrated Diary and Interview
data. For items unique to one or the other survey, the choice of which
survey to use as the source of data is obvious. However, there is
considerable overlap in coverage between the surveys. Because of the
overlap, the integration of the data presents the problem of determining
the appropriate survey component from which to select the expenditure
items. When data are available from both survey sources, the more
reliable of the two is selected as determined by statistical methods.
The selection of the survey source is evaluated periodically.
Data collection and processing
Due to differences in format and design, the
Interview Survey and the Diary Survey are collected
and processed separately. The U.S. Census Bureau, under
contract with BLS, carries out data collection for both.
In addition to its collection duties, the Census Bureau
does field editing and coding, checks consistency, ensures
quality control, and transmits the data to BLS. In preparing
the data for analysis and publication, BLS performs additional
review and editing procedures.
Quarterly Interview Survey. Beginning April 2003, Census
Field Representatives (FR) started collecting the Interview data
using a Computer Assisted Personal Interview (CAPI) instrument.
This was a major improvement from the paper and pencil data
collection that had been in place since 1980. The CAPI
instrument enforces question skip patterns, allows for data
confirmation of high expenditure values, and reduces processing
time. The FR performs some coding of expensesby selecting from
a predetermined listfor vehicle make and model, trip destination,
and job types for alterations, maintenance and repair.
Data are electronically transferred from the FRs laptop at
completion of the interview to the Census Master Control System.
The Census Bureaus Demographics Surveys Division then reformats
the data into SAS® datasets and does some special processing for
output to BLS (such as converting missing values to special characters
and merging data records into the required BLS output structure.)
Some data, like vehicle and mortgage records, are copied into an
input file that is loaded on the laptops for subsequent interviews
the next quarter. This way, a few fields are updated each quarter,
rather than recollecting the entire data record.
At BLS, a series of automated edits are applied to monthly data.
These edits check for inconsistencies, identify missing expenditure
amounts for later imputation, impute missing demographic variables,
calculate weights, and adjust data to include sales tax and exclude
business expenses or reimbursed expenditures.
Monthly data files are then combined into quarterly databases,
and a more extensive data review is carried out. This step includes
a review of the following: Counts and means by region, family
relationship coding inconsistencies, and selected extreme values for
expenditure and income categories. Other adjustments convert mortgage
and vehicle payments into principal and interest (using
associated data on the interest rate and term of the loan). In
addition, BLS verifies the various data transformations it performs.
Cases of questionable data values or relationships are investigated,
and errors are corrected prior to release of the data
for public use.
Three major types of data adjustment routinesimputation,
allocation, and time adjustmentimprove estimates derived from
the Interview Survey. Data imputation routines account for missing
or invalid entries and affect all fields in the database, except
assets. Missing or invalid attributes or expenditures are imputed.
Allocation routines are applied when respondents provide insufficient
detail to meet tabulation requirements. For example, combined
expenditures for the fuels and utilities group are allocated
among the components of that group, such as gas and electricity.
Time adjustment routines are used to classify expenditures by month,
prior to aggregation of the data to calendar-year expenditures.
Tabulations are made before and after the data adjustment routines,
to analyze the results.
The Survey implemented multiple imputations of income data
starting with the publication of the 2004 data. Prior to that,
only income data collected from complete income reporters were
published. However, even complete income reporters did not provide
information on all sources of income for which they reported receipt.
With the collection of bracketed income data starting in 2001 this
problem was reduced, but not eliminated. A limitation is that
bracketed data only provide a range in which income falls, rather
than a precise value for that income. In contrast, imputation
allows income values to be estimated when they are not reported.
In multiple imputations, several estimates are made for the same
consumer unit, and the average of these estimates is published.
Diary Survey. At the beginning of the 2-week collection period,
the Census Bureau interviewer, using the Household Characteristics
Questionnaire (a CAPI instrument), records demographic information on
members of each sampled consumer unit. At this time, the interviewer
also leaves the Diary questionnaireor daily expenditure recordwith
the consumer unit, to record expenditures for the week.
At the end of the first week, the interviewer collects the diary,
reviews the entries, answers any questions, and leaves a second diary.
The interviewer picks up the second diary at the end of the second
week and reviews the entries. During this time, the interviewer again
uses the Household Characteristics Questionnaire to collect
previous-year information on work experience and income. Each week
of a consumer units participation in the survey is treated as a
separate occurrence.
The Census Bureau performs preliminary processing activities,
including a number of data edits and adjustments. Data in the diaries
are reviewed during a field edit for completeness and consistency.
All notes are reviewed, so expenditure data can be transcribed
to the questionnaire for keying. In addition, item codes are
assigned to reported expenditure items, household and consumer
unit codes are assigned to each household member, and industry
and occupation codes are entered for each working member. After
an initial clerical screening, data are key-entered into electronic
formats and a computer file of the database containing these
data is produced and transmitted monthly to BLS, along with image
files of questionnaires.
Data are then processed by computer to calculate population
weights based on BLS specifications, impute demographic
characteristics for missing or inconsistent demographic data,
impute values for weeks worked when nonresponse is encountered,
and apply appropriate sales taxes to the expenditure items.
Using three monthly diary data files, BLS creates a quarterly
data base and screens it for invalid coding and inconsistent
relationships, as well as for extreme values recorded or keyed
erroneously. BLS then corrects any coding and extreme-value
errors found.
Two types of data adjustment routinesallocation and
imputationimprove the Diary Survey estimates. Allocation routines
transform reports of nonspecific items into specific ones. For
example, when respondents report expenditures for meat rather
than beef or pork, allocations are made, using proportions
derived from item-specific reports in other completed diaries.
BLS imputes missing attributes, such as age or sex or package type,
needed for mapping Diary expenditures. Income data from the Diary
Survey are processed in the same way as in the Interview Survey.
Next: Sample Design
|