Usual Weekly Earnings Explanatory Note
- 2 - Technical Note The estimates in this release were obtained from the Current Population Survey (CPS), which provides the basic information on the labor force, employment, and unemployment. The survey is conducted monthly for the Bureau of Labor Statistics by the U.S. Census Bureau from a scientifically selected national sample of about 60,000 households, with coverage in all 50 states and the District of Columbia. The earnings data are collected from one-quarter of the CPS monthly sample and are limited to wages and salaries. The data, therefore, exclude self-employment income. Information in this release will be made available to sensory impaired individuals upon request. Voice phone: (202) 691-5200; TDD message referral phone number: 1-800-877-8339. Reliability Statistics based on the CPS are subject to both sampling and nonsampling error. When a sample, rather than the entire population, is surveyed, there is a chance that the sample estimates may differ from the "true" population values they represent. The exact difference, or sampling error, varies de- pending on the particular sample selected, and this variability is measured by the standard error of the estimate. There is about a 90-percent chance, or level of confidence, that an estimate based on a sample will differ by no more than 1.6 standard errors from the "true" population value because of sampling error. BLS analyses are generally conducted at the 90-percent level of confidence. The CPS data also are affected by nonsampling error. Nonsampling error can occur for many reasons, including the failure to sample a segment of the population, inability to obtain information for all respondents in the sample, inability or unwillingness of respondents to provide correct information, and errors made in the collection or processing of the data. For a full discussion of the reliability of data from the CPS and informa- tion on estimating standard errors, see the Household Data section of the "Explanatory Notes and Estimates of Error" at http://www.bls.gov/cps/eetech_ methods.pdf. Definitions The principal definitions used in connection with the earnings series are described briefly below. Usual weekly earnings. Data represent earnings before taxes and other deductions and include any overtime pay, commissions, or tips usually received (at the main job in the case of multiple jobholders.) Prior to 1994, respondents were asked how much they usually earned per week. Since January 1994, respondents have been asked to identify the easiest way for them to report earnings (hourly, weekly, biweekly, twice monthly, monthly, annually, other) and how much they usually earn in the reported time period. Earnings reported on a basis other than weekly are converted to a weekly equivalent. The term "usual" is as perceived by the respondent. If the respondent asks for a definition of usual, interviewers are instructed to define the term as more than half the weeks worked during the past 4 or 5 months. - 3 - Medians (and other quantiles) of weekly earnings. The median (or upper limit of the second quartile) is the amount which divides a given earnings distribution into two equal groups, one having earnings above the median and the other having earnings below the median. Ten percent of a given distribution have earnings below the upper limit of the first decile (90 percent have higher earnings); 25 percent have earnings below the upper limit of the first quartile (75 percent have higher earnings); 75 percent have earnings below the upper limit of the third quartile (25 percent have higher earnings); and 90 percent have earnings below the upper limit of the ninth decile (10 percent have higher earnings). The estimating procedure places each reported or calculated weekly earnings value into $50-wide intervals which are centered around multiples of $50. The actual value is estimated through the linear interpolation of the interval in which the quantile boundary lies. Over-the-year changes in the medians (and other quantile boundaries) for specific groups may not necessarily be consistent with the movements estimated for the overall quantile boundary. The most common reasons for this possible anomaly are: (1) There could be a change in the relative weights of the subgroups. For example, the medians of both 16-to-24 year olds and those 25 years and over may rise; but if the lower-earning 16-to- 24 group accounts for a greatly increased share of the total, the overall median could actually fall. (2) There could be a large change in the shape of the distribution of reported earnings, particularly near a quantile boundary. This could be caused by survey observations that are clustered at rounded values, such as $250, $300, $400. An estimate lying in a $50-wide centered interval containing such a cluster or "spike" tends to change more slowly than one in other intervals. Wage and salary workers. Workers who receive wages, salaries, commissions, tips, payment in kind, or piece rates. The group includes employees in both the private and public sectors but, for the purposes of the earnings series, excludes all self-employed persons, regardless of whether or not their busi- nesses are incorporated. Full-time workers. Workers who usually work 35 hours or more per week at their sole or principal job. Part-time workers. Workers who usually work fewer than 35 hours per week at their sole or principal job. Constant dollars. The Consumer Price Index for All Urban Consumers (CPI-U) is used to convert current dollars to constant (1982) dollars. Hispanic or Latino ethnicity. Refers to persons who identified themselves in the enumeration process as being Spanish, Hispanic, or Latino. Persons whose ethnicity is identified as Hispanic or Latino may be of any race.
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Last Modified Date: July 17, 2008