Data Dictionary: Census 2000
you are here: choose a survey survey data set table variable details
Survey: Census 2000
Data Source: U.S. Census Bureau
Universe: Population 15 years and over
Variable Details
Relevant Documentation:
Excerpt from: Social Explorer, U.S. Census Bureau; 2000 Census of Population and Housing, Summary File 3: Technical Documentation, 2002.
 
Sex
The data on sex, which was asked of all people, were derived from answers to long-form questionnaire Item 3 and short-form questionnaire Item 5. Individuals were asked to mark either "male" or "female" to indicate their sex. For most cases in which sex was not reported, it was determined from the persons given (i.e., first) name and household relationship. Otherwise, sex was imputed according to the relationship to the householder and the age of the person. (For more information on imputation, see "Accuracy of the Data.")

Sex ratio
A measure derived by dividing the total number of males by the total number of females, and then multiplying by 100. This measure is rounded to the nearest tenth.

Comparability
A question on the sex of individuals has been included in every census. Census 2000 was the first time that first name was used for imputation of cases where sex was not reported.

Excerpt from: Social Explorer, U.S. Census Bureau; 2000 Census of Population and Housing, Summary File 3: Technical Documentation, 2002.
 
Work Status in 1999
The data on work status in 1999 were derived from answers to long-form questionnaire Item 30a, which was asked of a sample of the population 15 years old and over. People 16 years old and over who worked 1 or more weeks according to the criteria described below are classified as "Worked in 1999." All other people 16 years old and over are classified as "Did not work in 1999." Some earnings tabulations showing work status in 1999 include 15 year olds; these people, by definition, are classified as "Did not work in 1999."

Weeks worked in 1999
The data on weeks worked in 1999 were derived from answers to long-form questionnaire Item 30b, which was asked of people 15 years old and over who indicated in long-form questionnaire Item 30a that they worked in 1999. The data were tabulated for people 16 years old and over and pertain to the number of weeks during 1999 in which a person did any work for pay or profit (or took paid vacation or paid sick leave) or worked without pay on a family farm or in a family business. Weeks on active duty in the armed forces also are included as weeks worked.

Median weeks worked in 1999
Median weeks worked in 1999 divides the weeks worked distribution into two equal parts: one-half of the cases falling below the median weeks worked and one-half above the median. Median weeks worked in 1999 is computed on the basis of a standard distribution (see the "Standard Distributions" section under "Derived Measures"). Median weeks worked is rounded to the nearest whole number. (For more information on medians, see "Derived Measures".)

Usual hours worked per week in 1999
The data on usual hours worked in 1999 were derived from answers to long-form questionnaire Item 30c. This question was asked of people 15 years old and over who indicated that they worked in 1999 in Question 30a, and the data are tabulated for people 16 years old and over. The respondent was asked to report the number of hours usually worked during the weeks worked in 1999. If their hours varied considerably from week to week during 1999, the respondent was asked to report an approximate average of the hours worked each week. People 16 years old and over who reported that they usually worked 35 or more hours each week are classified as "Usually worked full time"; people who reported that they usually worked 1 to 34 hours each week are classified as "Usually worked part time."

Median usual hours worked per week in 1999
Median usual hours worked per week in 1999 divides the usual hours worked distribution into two equal parts: one-half of the cases falling below the median usual hours worked and one-half above the median. Median usual hours worked per week in 1999 is computed on the basis of a standard distribution (see the "Standard Distributions" section under "Derived Measures"). Median usual hours worked per week is rounded to the nearest whole hour. (For more information on medians, see "Derived Measures".)

Aggregate usual hours worked per week in 1999
The aggregate usual hours worked per week in 1999 is the number obtained by summing across the usual hours worked values of all people who worked in 1999. (Note that there is one usual hours value for each worker, so the number of items summed equals the number of workers.)

Mean usual hours worked per week in 1999
Mean usual hours worked per week is calculated by dividing the aggregate number of usual hours worked per week worked in 1999 by the total number of people who worked in 1999. Mean usual hours worked per week is rounded to the nearest tenth. (For more information on means, see "Derived Measures".)

Full-time, year-round workers
'Full-time, year-round workers' consists of people 16 years old and over who usually worked 35 hours or more per week for 50 to 52 weeks in 1999. The term "worker" in these concepts refers to people classified as Worked in 1999 as defined above. The term worked in these concepts means "worked one or more weeks in 1999" as defined above under "Weeks Worked in 1999."

Limitation of the data
It is probable that data on the number of people who worked in 1999 and on the number of weeks worked are understated since there was probably a tendency for respondents to forget intermittent or short periods of employment or to exclude weeks worked without pay. There may also have been a tendency for people not to include weeks of paid vacation among their weeks worked, which would result in an underestimate of the number of people who worked "50 to 52 weeks."

Comparability
The data on weeks worked collected in Census 2000 are comparable with data from the 1960 to 1990 censuses, but may not be entirely comparable with data from the 1940 and 1950 censuses. Starting with the 1960 census, two separate questions have been used to obtain this information. The first identifies people with any work experience during the year and, thus, indicates those people for whom the question about number of weeks worked applies. In 1940 and 1950, the questionnaires contained only a single question on number of weeks worked. In 1970, people responded to the question on weeks worked by indicating one of six weeks-worked intervals. In 1980 and 1990, people were asked to enter the specific number of weeks they worked.

Worker
The terms "worker" and "work" appear in connection with several subjects: employment status, journey-to-work, class of worker, and work status in 1999. Their meaning varies and, therefore, should be determined by referring to the definition of the subject in which they appear. When used in the concepts "Workers in Family," "Workers in Family in 1999," and "Full-Time, Year-Round Workers," the term "worker" relates to the meaning of work defined for the "Work Status in 1999" subject.

Excerpt from: Social Explorer, U.S. Census Bureau; 2000 Census of Population and Housing, Summary File 3: Technical Documentation, 2002.
 
Income in 1999
The data on income in 1999 were derived from answers to long-form questionnaire Items 31 and 32, which were asked of a sample of the population 15 years old and over. "Total income" is the sum of the amounts reported separately for wage or salary income; net self-employment income; interest, dividends, or net rental or royalty income or income from estates and trusts; social security or railroad retirement income; Supplemental Security Income (SSI); public assistance or welfare payments; retirement, survivor, or disability pensions; and all other income.

"Earnings" are defined as the sum of wage or salary income and net income from selfemployment. "Earnings" represent the amount of income received regularly for people 16 years old and over before deductions for personal income taxes, social security, bond purchases, union dues, medicare deductions, etc.

Receipts from the following sources are not included as income: capital gains, money received from the sale of property (unless the recipient was engaged in the business of selling such property); the value of income "in kind" from food stamps, public housing subsidies, medical care, employer contributions for individuals, etc.; withdrawal of bank deposits; money borrowed; tax refunds; exchange of money between relatives living in the same household; and gifts and lump-sum inheritances, insurance payments, and other types of lump-sum receipts.

Income Type in 1999
The eight types of income reported in the census are defined as follows:

1.Wage or salary income
Wage or salary income includes total money earnings received for work performed as an employee during the calendar year 1999. It includes wages, salary, armed forces pay, commissions, tips, piece-rate payments, and cash bonuses earned before deductions were made for taxes, bonds, pensions, union dues, etc.

2.Self-employment income
Self-employment income includes both farm and nonfarm self-employment income. Nonfarm self-employment income includes net money income (gross receipts minus expenses) from ones own business, professional enterprise, or partnership. Gross receipts include the value of all goods sold and services rendered. Expenses include costs of goods purchased, rent, heat, light, power, depreciation charges, wages and salaries paid, business taxes (not personal income taxes), etc. Farm self-employment income includes net money income (gross receipts minus operating expenses) from the operation of a farm by a person on his or her own account, as an owner, renter, or sharecropper. Gross receipts include the value of all products sold, government farm programs, money received from the rental of farm equipment to others, and incidental receipts from the sale of wood, sand, gravel, etc. Operating expenses include cost of feed, fertilizer, seed, and other farming supplies, cash wages paid to farmhands, depreciation charges, cash rent, interest on farm mortgages, farm building repairs, farm taxes (not state and federal personal income taxes), etc. The value of fuel, food, or other farm products used for family living is not included as part of net income.

3.Interest, dividends, or net rental income
Interest, dividends, or net rental income includes interest on savings or bonds, dividends from stockholdings or membership in associations, net income from rental of property to others and receipts from boarders or lodgers, net royalties, and periodic payments from an estate or trust fund.

4.Social security income
Social security income includes social security pensions and survivors benefits, permanent disability insurance payments made by the Social Security Administration prior to deductions for medical insurance, and railroad retirement insurance checks from the U.S. government. Medicare reimbursements are not included.

5.Supplemental Security Income (SSI)
Supplemental Security Income (SSI) is a nationwide U.S. assistance program administered by the Social Security Administration that guarantees a minimum level of income for needy aged, blind, or disabled individuals. The census questionnaire for Puerto Rico asked about the receipt of SSI; however, SSI is not a federally administered program in Puerto Rico. Therefore, it is probably not being interpreted by most respondents as the same as SSI in the United States. The only way a resident of Puerto Rico could have appropriately reported SSI would have been if they lived in the United States at any time during calendar year 1999 and received SSI.

6.Public assistance income
Public assistance income includes general assistance and Temporary Assistance to Needy Families (TANF). Separate payments received for hospital or other medical care (vendor payments) are excluded. This does not include Supplemental Security Income (SSI).


7.Retirement income
Retirement income includes: (1) retirement pensions and survivor benefits from a former employer; labor union; or federal, state, or local government; and the U.S. military; (2) income from workers compensation; disability income from companies or unions; federal, state, or local government; and the U.S. military; (3) periodic receipts from annuities and insurance; and (4) regular income from IRA and KEOGH plans. This does not include social security income.

8.All other income
All other income includes unemployment compensation, Veterans Administration (VA) payments, alimony and child support, contributions received periodically from people not living in the household, military family allotments, and other kinds of periodic income other than earnings.

Income of households
This includes the income of the householder and all other individuals 15 years old and over in the household, whether they are related to the householder or not. Because many households consist of only one person, average household income is usually less than average family income. Although the household income statistics cover calendar year 1999, the characteristics of individuals and the composition of households refer to the time of enumeration (April 1, 2000). Thus, the income of the household does not include amounts received by individuals who were members of the household during all or part of calendar year 1999 if these individuals no longer resided in the household at the time of enumeration. Similarly, income amounts reported by individuals who did not reside in the household during 1999 but who were members of the household at the time of enumeration are included. However, the composition of most households was the same during 1999 as at the time of enumeration.

Income of families
In compiling statistics on family income, the incomes of all members 15 years old and over related to the householder are summed and treated as a single amount. Although the family income statistics cover calendar year 1999, the characteristics of individuals and the composition of families refer to the time of enumeration (April 1, 2000). Thus, the income of the family does not include amounts received by individuals who were members of the family during all or part of calendar year 1999 if these individuals no longer resided with the family at the time of enumeration. Similarly, income amounts reported by individuals who did not reside with the family during 1999 but who were members of the family at the time of enumeration are included. However, the composition of most families was the same during 1999 as at the time of enumeration.

Income of individuals
Income for individuals is obtained by summing the eight types of income for each person 15 years old and over. The characteristics of individuals are based on the time of enumeration (April 1, 2000), even though the amounts are for calendar year 1999.

Median income
The median divides the income distribution into two equal parts: one-half of the cases falling below the median income and one-half above the median. For households and families, the median income is based on the distribution of the total number of households and families including those with no income. The median income for individuals is based on individuals 15 years old and over with income. Median income for households, families, and individuals is computed on the basis of a standard distribution (see the "Standard Distributions" section under "Derived Measures"). Median income is rounded to the nearest whole dollar. Median income figures are calculated using linear interpolation if the width of the interval containing the estimate is $2,500 or less. If the width of the interval containing the estimate is greater than $2,500, Pareto interpolation is used. (For more information on medians and interpolation, see "Derived Measures".)

Aggregate income
Aggregate income is the sum of all incomes for a particular universe. Aggregate income is subject to rounding, which means that all cells in a matrix are rounded to the nearest hundred dollars. (For more information, see "Aggregate" under "Derived Measures".)

Mean income
Mean income is the amount obtained by dividing the aggregate income of a particular statistical universe by the number of units in that universe. Thus, mean household income is obtained by dividing total household income by the total number of households. (The aggregate used to calculate mean income is rounded. For more information, see "Aggregate income.")

For the various types of income, the means are based on households having those types of income. For households and families, the mean income is based on the distribution of the total number of households and families including those with no income. The mean income for individuals is based on individuals 15 years old and over with income. Mean income is rounded to the nearest whole dollar.

Care should be exercised in using and interpreting mean income values for small subgroups of the population. Because the mean is influenced strongly by extreme values in the distribution, it is especially susceptible to the effects of sampling variability, misreporting, and processing errors. The median, which is not affected by extreme values, is, therefore, a better measure than the mean when the population base is small. The mean, nevertheless, is shown in some data products for most small subgroups because, when weighted according to the number of cases, the means can be added to obtained summary measures for areas and groups other than those shown in census tabulations. (For more information on means, see "Derived Measures".)

Earnings
Earnings are defined as the sum of wage or salary income and net income from self-employment. "Earnings" represent the amount of income received regularly for people 16 years old and over before deductions for personal income taxes, social security, bond purchases, union dues, medicare deductions, etc.

Median earnings
The median divides the earnings distribution into two equal parts: one-half of the cases falling below the median earnings and one-half above the median. Median earnings is restricted to individuals 16 years old and over and is computed on the basis of a standard distribution (see the "Standard Distributions" section under "Derived Measures"). Median earnings figures are calculated using linear interpolation if the width of the interval containing the estimate is $2,500 or less. If the width of the interval containing the estimate is greater than $2,500, Pareto interpolation is used. (For more information on medians and interpolation, see Derived Measures.)

Aggregate earnings
Aggregate earnings are the sum of wage/salary and net self-employment income for a particular universe of people 16 years old and over. Aggregate earnings are subject to rounding, which means that all cells in a matrix are rounded to the nearest hundred dollars. (For more information, see "Aggregate" under "Derived Measures".)

Mean earnings
Mean earnings is calculated by dividing aggregate earnings by the population 16 years old and over with earnings. (The aggregate used to calculate mean earnings is rounded. For more information, see "Aggregate earnings.") Mean earnings is rounded to the nearest whole dollar. (For more information on means, see "Derived Measures".)

Per capita income
Per capita income is the mean income computed for every man, woman, and child in a particular group. It is derived by dividing the total income of a particular group by the total population in that group. (The aggregate used to calculate per capita income is rounded. For more information, see "Aggregate" under "Derived Measures".) Per capita income is rounded to the nearest whole dollar. (For more information on means, see "Derived Measures".)

Limitation of the data
Since answers to income questions are frequently based on memory and not on records, many people tended to forget minor or sporadic sources of income and, therefore, underreport their income. Underreporting tends to be more pronounced for income sources that are not derived from earnings, such as public assistance, interest, dividends, and net rental income.

Extensive computer editing procedures were instituted in the data processing operation to reduce some of these reporting errors and to improve the accuracy of the income data. These procedures corrected various reporting deficiencies and improved the consistency of reported income items associated with work experience and information on occupation and class of worker. For example, if people reported they were self employed on their own farm, not incorporated, but had reported wage and salary earnings only, the latter amount was shifted to self-employment income. Also, if any respondent reported total income only, the amount was generally assigned to one of the types of income items according to responses to the work experience and class-of-worker questions. Another type of problem involved nonreporting of income data. Where income information was not reported, procedures were devised to impute appropriate values with either no income or positive or negative dollar amounts for the missing entries. (For more information on imputation, see "Accuracy of the Data.")

In income tabulations for households and families, the lowest income group (for example, less than $10,000) includes units that were classified as having no 1999 income. Many of these were living on income "in kind," savings, or gifts, were newly created families, or were families in which the sole breadwinner had recently died or left the household. However, many of the households and families who reported no income probably had some money income that was not reported in the census.

Comparability
The income data collected in the 1970, 1980, and 1990 censuses are similar to Census 2000 data, but there are variations in the detail of the questions. In 1990, income information for 1989 was collected from people in approximately 17 percent of all housing units and group quarters. Each person 15 years old and over was required to report:
  • Wage or salary income
  • Net nonfarm self-employment income
  • Net farm self-employment income
  • Interest, dividend, or net rental or royalty income
  • Social security or railroad retirement income
  • Supplemental Security Income (SSI), Aid to Families With Dependent Children (AFDC), or other
  • public assistance income
  • Retirement, survivor, or disability income
  • Income from all other sources
Since the number of respondents reporting farm self-employment income has become smaller over the years, the farm and nonfarm self-employment items were combined into one item for Census 2000. Data users are still able to obtain an estimate of "farm self-employment" income by looking at net self-employment income in combination with other labor force related questions such as "occupation of longest job." Supplemental Security Income (SSI) was asked separately from other public assistance income or welfare received from a state or local welfare office in Census 2000.

Between the 1990 census and Census 2000, there were minor differences in the processing of the data. In both censuses, all people with missing values in one or more of the detailed type of income items were designated as allocated. Each missing entry was imputed either as a "no" or as a dollar amount. If total income was reported and one or more of the type of income fields was not answered, then the entry in total income generally was assigned to one of the income types according to the socioeconomic characteristics of the income recipient. This person was designated as unallocated.

In 2000 and 1990, all nonrespondents with income not reported (whether householders or other people) were assigned the reported income of people with similar characteristics. (For more information on imputation, see "Accuracy of the Data.")

In 1980, income information for 1979 was collected from people in approximately 19 percent of all housing units and group quarters. Each person 15 years old and over was required to report:
  • Wage or salary income
  • Net nonfarm self-employment income
  • Net farm self-employment income
  • Interest, dividend, or net rental or royalty income
  • Social security or railroad retirement income
  • Supplemental Security Income (SSI), Aid to Families With Dependent Children (AFDC), or other public assistance income
  • Income from all other sources
There was a difference in the method of computer derivation of aggregate income from individual amounts. In the 1980 census, income amounts less than $100,000 were coded in tens of dollars, and amounts of $100,000 or more were coded in thousands of dollars; $5 was added to each amount coded in tens of dollars and $500 to each amount coded in thousands of dollars. Entries of $999,000 or more were treated as $999,500 and losses of $9,999 or more were treated as minus $9,999. In the 1990 and 2000 censuses, income amounts less than $999,999 were keyed to the nearest dollar. Amounts of $999,999 or more were treated as $999,999 and losses of $9,999 or more were treated as minus $9,999 in all of the computer derivations of aggregate income.

In 1970, information on income in 1969 was obtained from all members in every fifth housing unit 14 years old and over and small group quarters (less than 15 people) and every fifth person in all other group quarters. Each person 14 years old and over was required to report:
  • Wage or salary income
  • Net nonfarm self-employment income
  • Net farm self-employment income
  • Social security or railroad retirement income
  • Supplemental Security Income (SSI), Aid to Families With Dependent Children (AFDC), or other public assistance income
  • Income from all other sources
If a person reported a dollar amount in wage or salary, net nonfarm self-employment income, or net farm self-employment income, the person was considered as unallocated only if no further dollar amounts were imputed for any additional missing entries.

In 1960, data on income were obtained from all members 14 years old and over in every fourth housing unit and from every fourth person 14 years old and over living in group quarters. Each person was required to report wage or salary income, net self-employment income, and income other than earnings received in 1959. An assumption was made in the editing process that no other type of income was received by a person who reported the receipt of either wage and salary income or self-employment but who had failed to report the receipt of other money income.

For several reasons, the income data shown in census tabulations are not directly comparable with those that may be obtained from statistical summaries of income tax returns. Income, as defined for federal tax purposes, differs somewhat from the Census Bureau concept. Moreover, the coverage of income tax statistics is different because of the exemptions of people having small amounts of income and the inclusion of net capital gains in tax returns. Furthermore, members of some families file separate returns and others file joint returns; consequently, the income reporting unit is not consistently either a family or a person.

The earnings data shown in census tabulations are not directly comparable with earnings records of the Social Security Administration. The earnings record data for 1999 excluded the earnings of some civilian government employees, some employees of nonprofit organizations, workers covered by the Railroad Retirement Act, and people not covered by the program because of insufficient earnings. Because census data are obtained from household questionnaires, they may differ from Social Security Administration earnings record data, which are based upon employers reports and the federal income tax returns of self-employed people.

The Bureau of Economic Analysis (BEA) of the Department of Commerce publishes annual data on aggregate and per-capita personal income received by the population for states, metropolitan areas, and selected counties. Aggregate income estimates based on the income statistics shown in census products usually would be less than those shown in the BEA income series for several reasons. The Census Bureau data are obtained directly from households; whereas, the BEA income series is estimated largely on the basis of data from administrative records of business and governmental sources. Moreover, the definitions of income are different. The BEA income series includes some items not included in the income data shown in census publications, such as income "in kind," income received by nonprofit institutions, the value of services of banks and other financial intermediaries rendered to people without the assessment of specific charges, medicare payments, and the income of people who died or emigrated prior to April 1, 2000. On the other hand, the census income data include contributions for support received from people not residing in the same household if the income is received on a regular basis.

In comparing income data for 1999 with earlier years, it should be noted that an increase or decrease in money income does not necessarily represent a comparable change in real income, unless adjustments for changes in prices are made.