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Technical Note

The estimates in this report were obtained from the Current 

Population Survey (CPS), a national monthly sample survey 

of approximately 60,000 households, which provides a 

wide range of information on the labor force, employment, 

and unemployment. Earnings and union affiliation data are 

collected from one-fourth of the CPS monthly sample. The 

survey is conducted for the U.S. Bureau of Labor Statistics 

by the U.S. Census Bureau, using a scientifically-selected 

national sample with coverage in all 50 States and the District 

of Columbia.

Material in this report is in the public domain and may be 

reproduced without permission. This information is available 

to sensory-impaired individuals on request. Voice phone: 

(202) 691-5200; Federal Relay Service: 1-800-877-8339.

Reliability of the Estimates

Statistics based on the CPS are subject to both sampling and 

nonsampling error. When a sample, rather than an 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 depending 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 generally are conducted at the 

90-percent level of confidence.

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 data. The full extent of nonsampling error is unknown, 

but special studies have been conducted to quantify some 

sources of such error in the CPS. For further discussion 

of the reliability of data from the CPS and information 

on estimating standard errors, see the Household Data 

technical documentation provided at http://www.bls.gov/cps/

documentation.htm#reliability.

Concepts and Definitions

Civilian noninstitutional population. Included are persons 

16 years of age and older residing in the 50 States and the 

District of Columbia who are not confined to institutions (for 

example, correctional facilities and residential nursing and 

mental health care facilities) and who are not on active duty 

in the Armed Forces.

Civilian labor force. This group comprises all persons 

classified as employed or unemployed.

Employed persons. Employed persons are those who, during 

the survey week, (a) did any work at all as paid civilians; (b) 

worked in their own business or profession or on their own 

farm; (c) worked 15 hours or more as unpaid workers in a 

family business; or (d) were temporarily absent from their 

jobs because of illness, vacation, bad weather, or another 

reason.

Unemployed persons. Unemployed persons are those who 

had no employment during the survey week, were available 

for work at that time, and made specific efforts to find 

employment sometime in the prior 4 weeks. Persons laid off 

from their former jobs and awaiting recall did not need to be 

looking for work to be classified as unemployed.

Civilian labor force participation rate. This rate is the 

civilian labor force as a percent of the civilian noninstitutional 

population.

Employment-population ratio. This ratio represents the 

proportion of the population that is employed.

Unemployment rate. This rate represents the number of 

unemployed persons as a percent of the civilian labor force.

Race. White, Black or African American, and Asian are 

terms used to describe the race of persons. Persons in these 

categories are those who selected that race group only. Data 

for the remaining race categories—American Indian or 

Alaska Native, Native Hawaiian or Other Pacific Islander, 

and persons who selected more than one race category—

are included in totals but are not shown separately because 

the number of survey respondents was too small to develop 

estimates of sufficient quality for publication. In the survey 

process, race is determined by the household respondent.

Hispanic or Latino ethnicity. This term refers to persons 

who identified themselves in the survey as being Spanish, 

Hispanic, or Latino. Persons whose ethnicity is identified as 

Hispanic or Latino may be of any race.

Family. A family is a group of two or more persons residing 

together who are related by birth, marriage, or adoption. 

Families are classified either as married-couple families or 

as families maintained by women or men without spouses. 

Families include those with children under 18 in the home 

and those without children under 18.

Self-employed workers. Self-employed workers are those 

who work for profit or fees in their own business, profession, 

trade, or farm. Unincorporated self-employed are included 

in the self-employed category. Self-employed persons whose 

businesses are incorporated are included with wage and 

salary workers.
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Wage and salary workers. These are workers who receive 

wages, salaries, commissions, tips, payment in kind, or piece 

rates. The group includes employees in both the private 

and public sectors. Union membership and earnings data of 

wage and salary workers exclude all self-employed workers, 

both those with incorporated businesses and those with 

unincorporated businesses.

Hourly paid workers. Workers who are paid an hourly wage 

are a subset of wage and salary workers. Historically, workers 

paid an hourly wage have made up approximately three-fifths 

of all wage and salary workers. Estimates of median usual 

weekly earnings in this report are based on the earnings of all 

workers—those paid by the hour and those paid a salary or 

on some other basis.

Usual weekly earnings. Data are collected on wages and 

salaries before taxes and other deductions and include any 

overtime pay, commissions, or tips usually received (at the 

principal job in the case of multiple jobholders). Earnings of 

self-employed workers are excluded, regardless of whether 

their businesses are incorporated. Prior to 1994, respondents 

were asked to report earnings 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, or other) and how much they 

usually earn in the reported 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.”

Median weekly earnings. The median is the amount that 

divides a given earnings distribution into two equal groups: 

one having earnings above the median and the other having 

earnings below the median. The BLS estimating procedure 

for determining the median of an earnings distribution places 

each reported or calculated weekly earnings value into a $50-

wide interval that is centered on a multiple of $50. The value 

of the median is estimated through a linear interpolation of 

the interval in which the median lies. Over-the-year changes 

in the medians for specific groups may not necessarily be 

consistent with the movements estimated for the overall 

group boundary. The most common reasons for this possible 

anomaly follow: (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 age 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. This could be caused by 

survey observations that are clustered at rounded values, for 

example, $300, $400, or $500. 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. 

Consider, for example, the calculation of the median for 

a multipeaked distribution that shifts over time. As such a 

distribution shifts, the median does not necessarily move at 

the same rate. Specifically, the median takes relatively more 

time to move through a frequently reported interval but, 

once above the upper limit of such an interval, it can move 

relatively quickly to the next frequently reported earnings 

interval. BLS procedures for estimating medians mitigate 

such irregular movements of the measures; however, users 

should be cautious of these effects when evaluating shortterm changes in the medians, and in ratios of the medians.

Hours at work. These are the actual hours worked (at all jobs) 

during the survey reference week. For example, persons 

who normally work 40 hours a week but were off during 

the Columbus Day holiday would be reported as working 32 

hours, even if they were paid for the holiday.

Usual hours, or usual full- or part-time status. Data on 

persons “at work” exclude persons who were temporarily 

absent from a job and therefore classified in the zero-hours 

worked category, “with a job but not at work.” These are 

persons who were absent from their jobs for the entire 

week for reasons such as bad weather, vacation, illness, or 

involvement in a labor dispute. To differentiate a person’s 

normal schedule from his or her activity during the reference 

week, persons also are classified according to their usual 

full- or part-time status. In this context, full-time workers 

are those who usually work 35 hours or more (at all jobs 

combined) per week. This group includes some individuals 

who worked less than 35 hours in the reference week for 

either economic or noneconomic reasons and those who were 

temporarily absent from work. Similarly, part-time workers 

are those who usually work less than 35 hours per week (at 

all jobs), regardless of the number of hours worked in the 

reference week. This may include some individuals who 

actually worked more than 34 hours in the reference week, as 

well as those who were temporarily absent from work.

Occupation and industry. This information applies to the job 

held during the reference week. Persons with two or more 

jobs are classified in the occupation and industry at which 

they worked the greatest number of hours. The occupational 

and industry classification of CPS data is based on the 2010 

Census occupational classification and the 2007 Census 

industrial classification systems, which are derived from the 

2010 Standard Occupation Classification (SOC) and the 2007 

North American Industry Classification (NAICS). Additional 

information about these classifications is available online at 

http://www.bls.gov/cps/cpsoccind.htm.

Work experience. These data reflect work activity during 

the calendar year and are obtained from the Annual Social 

and Economic Supplement (ASEC) to the CPS. Estimates of 

persons who worked were based on “yes” responses to the 

following questions in the ASEC: “Did you work at a job or 

business at any time during [the survey reference year]?” or 

“Did you do any temporary, part-time, or seasonal work even 
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for a few days during [the survey reference year]?” Since 

the reference period is a full year, the number of persons 

with some employment or unemployment greatly exceeds 

the average levels for any given month, which are based on 

a 1-week reference period, and the corresponding annual 

averages of monthly estimates.

Poverty classification. Poverty statistics presented in this 

report are based on definitions developed by the Social 

Security Administration in 1964 and revised by the Federal 

interagency committees in 1969 and 1981. These definitions 

originally were based on the Department of Agriculture’s 

Economy Food Plan and reflected the different consumption 

requirements of families, based on factors such as family 

size and the number of children under 18 years of age. 

The actual poverty thresholds vary in accordance with the 

makeup of the family. Poverty thresholds are updated each 

year to reflect changes in the Consumer Price Index for 

All Urban Consumers (CPI-U). The thresholds do not vary 

geographically. For more information on poverty data and 

thresholds, see http://www.census.gov/hhes/www/poverty/

poverty.html.