Data Dictionary: Census 2000
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Survey: Census 2000
Data Source: U.S. Census Bureau
Table: PCT61. Ratio of Income in 1999 to Poverty Level of Families by Family Type by Presence and Age of Related Children
Universe: Families
Table Details
PCT61. Ratio of Income in 1999 to Poverty Level of Families by Family Type by Presence and Age of Related Children
Universe: Families
Variable Label
PCT061001
PCT061002
PCT061003
PCT061004
PCT061005
PCT061006
PCT061007
PCT061008
PCT061009
PCT061010
PCT061011
PCT061012
PCT061013
PCT061014
PCT061015
PCT061016
PCT061017
PCT061018
PCT061019
PCT061020
PCT061021
PCT061022
PCT061023
PCT061024
PCT061025
PCT061026
PCT061027
PCT061028
PCT061029
PCT061030
PCT061031
PCT061032
PCT061033
PCT061034
PCT061035
PCT061036
PCT061037
PCT061038
PCT061039
PCT061040
PCT061041
PCT061042
PCT061043
PCT061044
PCT061045
PCT061046
PCT061047
PCT061048
PCT061049
PCT061050
PCT061051
PCT061052
PCT061053
PCT061054
PCT061055
PCT061056
PCT061057
PCT061058
PCT061059
PCT061060
PCT061061
PCT061062
PCT061063
PCT061064
PCT061065
PCT061066
PCT061067
PCT061068
PCT061069
PCT061070
PCT061071
PCT061072
PCT061073
PCT061074
PCT061075
PCT061076
PCT061077
PCT061078
PCT061079
PCT061080
PCT061081
Relevant Documentation:
Excerpt from: Social Explorer, U.S. Census Bureau; 2000 Census of Population and Housing, Summary File 3: Technical Documentation, 2002.
 
Ratio
This is a measure of the relative size of one number to a second number expressed as the quotient of the first number divided by the second. For example, the sex ratio is calculated by dividing the total number of males by the total number of females, and then multiplying by 100.


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.

Excerpt from: Social Explorer, U.S. Census Bureau; 2000 Census of Population and Housing, Summary File 3: Technical Documentation, 2002.
 
Poverty Status in 1999
The poverty data were derived from answers to long-form questionnaire Items 31 and 32, the same questions used to derive income data. (For more information, see "Income in 1999.") The Census Bureau uses the federal governments official poverty definition. The Social Security Administration (SSA) developed the original poverty definition in 1964, which federal interagency committees subsequently revised in 1969 and 1980. The Office of Management and Budgets (OMBs) Directive 14 prescribes this definition as the official poverty measure for federal agencies to use in their statistical work.

Derivation of the Current Poverty Measure
When the Social Security Administration (SSA) created the poverty definition in 1964, it focused on family food consumption. The U.S. Department of Agriculture (USDA) used its data about the nutritional needs of children and adults to construct food plans for families. Within each food plan, dollar amounts varied according to the total number of people in the family and the familys composition, such as the number of children within each family. The cheapest of these plans, the Economy Food Plan, was designed to address the dietary needs of families on an austere budget. Since the USDAs 1955 Food Consumption Survey showed that families of three or more people across all income levels spent roughly one-third of their income on food, the SSA multiplied the cost of the Economy Food Plan by three to obtain dollar figures for the poverty thresholds. Since the Economy Food Plan budgets varied by family size and composition, so too did the poverty thresholds. For 2-person families, the thresholds were adjusted by slightly higher factors because those households had higher fixed costs. Thresholds for unrelated individuals were calculated as a fixed proportion of the corresponding thresholds for 2-person families.

The poverty thresholds are revised annually to allow for changes in the cost of living as reflected in the Consumer Price Index (CPI-U). The poverty thresholds are the same for all parts of the country - they are not adjusted for regional, state or local variations in the cost of living. For a detailed discussion of the poverty definition, see U.S. Census Bureau, Current Population Reports, " Poverty in the United States: 1999," P-60-210.

How Poverty Status is Determined
The poverty status of families and unrelated individuals in 1999 was determined using 48 thresholds (income cutoffs) arranged in a two dimensional matrix. The matrix consists of family size (from 1 person to 9 or more people) cross-classified by presence and number of family members under 18 years old (from no children present to 8 or more children present). Unrelated individuals and 2-person families were further differentiated by the age of the reference person (RP) (under 65 years old and 65 years old and over).

To determine a person's poverty status, one compares the persons total family income with the poverty threshold appropriate for that persons family size and composition (see table below). If the total income of that persons family is less than the threshold appropriate for that family, then the person is considered poor, together with every member of his or her family. If a person is not living with anyone related by birth, marriage, or adoption, then the persons own income is compared with his or her poverty threshold.

Weighted average thresholds
Even though the official poverty data are based on the 48 thresholds arranged by family size and number of children within the family, data users often want to get an idea of the "average" threshold for a given family size. The weighted average thresholds provide that summary. They are weighted averages because for any given family size, families with a certain number of children may be more or less common than families with a different number of children. In other words, among 3-person families, there are more families with two adults and one child than families with three adults. To get the weighted average threshold for families of a particular size, multiply each threshold by the number of families for whom that threshold applies; then add up those products, and divide by the total number of families who are of that family size.

For example, for 3-person families, 1999 weighted thresholds were calculated in the following way using information from the 2000 Current Population Survey:

Family type Number of families Threshold  
No children (three adults) 5,213 * $13,032 = $67,935,816
One child (two adults) 8,208 * $13,410 = $110,069,280
Two children (one adult) 2,656 * $13,423 = $35,651,488
Totals 16,077       $213,656,584
Source: Current Population Survey, March 2000.


Dividing $213,656,584 by 16,077 (the total number of 3-person families) yields $13,290, the weighted average threshold for 3-person families. Please note that the thresholds are weighted not just by the number of poor families, but by all families for which the thresholds apply: the thresholds are used to determine which families are at or above poverty, as well as below poverty.

Individuals for whom poverty status is determined
Poverty status was determined for all people except institutionalized people, people in military group quarters, people in college dormitories, and unrelated individuals under 15 years old. These groups also were excluded from the numerator and denominator when calculating poverty rates. They are considered neither "poor" nor "nonpoor."

Specified poverty levels
For various reasons, the official poverty definition does not satisfy all the needs of data users. Therefore, some of the data reflect the number of people below different percentages of the poverty level. These specified poverty levels are obtained by multiplying the official thresholds by the appropriate factor. For example, the average income cutoff at 125 percent of the poverty level was $21,286 ($17,029 x 1.25) in 1999 for family of four people.

Poverty Threshold in 1999, by Size of Family and Number of Related Children Under 18 Years Old (Dollars)
Size of family unit Weighted average threshold Related children under 18 years old
    None One Two Three Four Five Six Seven Eight or more
One person (unrelated individual) 8501                  
    Under 65 years old 8667 8667                
    65 years old and over 7990 7990                
Two people 10869                  
    Householder under 65 years old 11214 11156 11483              
    Householder 65 years old and over 10075 10070 11440              
Three people 13290 13032 13410 13423            
Four people 17029 17184 17465 16895 16954          
Five people 20127 20723 21024 20380 19882 19578        
Six people 22727 23835 23930 23436 22964 22261 21845      
Seven people 25912 27425 27596 27006 26595 25828 24934 23953    
Eight people 28967 30673 30944 30387 29899 29206 28327 27412 27180  
Nine people or more 34417 36897 37076 36583 36169 35489 34554 33708 33499 32208


Income deficit
Income deficit represents the difference between the total income of families and unrelated individuals below the poverty level and their respective poverty thresholds. In computing the income deficit, families reporting a net income loss are assigned zero dollars and for such cases the deficit is equal to the poverty threshold. This measure provides an estimate of the amount which would be required to raise the incomes of all poor families and unrelated individuals to their respective poverty thresholds. The income deficit is thus a measure of the degree of the impoverishment of a family or unrelated individual. However, please use caution when comparing the average deficits of families with different characteristics. Apparent differences in average income deficits may, to some extent, be a function of differences in family size.

Aggregate income deficit
Aggregate income deficit refers only to those families or unrelated individuals who are classified as below the poverty level. It is defined as the group (e.g., type of family) sum total of differences between the appropriate threshold and total family income or total personal income. Aggregate income deficit 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 deficit
Mean income deficit represents the amount obtained by dividing the total income deficit for a group below the poverty level by the number of families (or unrelated individuals) in that group. (The aggregate used to calculate mean income deficit is rounded. For more information, see "Aggregate income deficit.") As mentioned above, please use caution when comparing mean income deficits of families with different characteristics, as apparent differences may to some extent be a function of differences in family size. Mean income deficit is rounded to the nearest whole dollar. (For more information on means, see "Derived Measures".)

Comparability
The poverty definition used in the 1980 census and later differed slightly from the one used in the 1970 census. Three technical modifications were made to the definition used in the 1970 census:

1. Beginning with the 1980 census, the Office of Management and Budget eliminated any distinction between thresholds for "families with a female householder with no husband present" and all other families. The new thresholds - which apply to all families regardless of the householder's sex - were a weighted average of the old thresholds.

2. The Office of Management and Budget eliminated any differences between farm families and nonfarm families, and farm and nonfarm unrelated individuals. In the 1970 census, the farm thresholds were 85 percent of those for nonfarm families; whereas, in 1980 and later, the same thresholds were applied to all families and unrelated individuals regardless of residence.

3. The thresholds by size of family were extended from seven or more people in 1970 to nine or more people in 1980 and later.

These changes resulted in a minimal increase in the number of poor at the national level. For a complete discussion of these modifications and their impact, see U.S. Census Bureau, Current Population Reports, " Characteristics of the Population Below the Poverty Level: 1980," P-60, No. 133.

With respect to poverty, the population covered in the 1970 census was almost the same as that covered in the 1980 census and later. The only difference was that in 1980 and after, unrelated individuals under 15 years old were excluded from the poverty universe, while in 1970, only those under age 14 were excluded. The limited poverty data from the 1960 census excluded all people in group quarters and included all unrelated individuals regardless of age. It was unlikely that these differences in population coverage would have had significant impact when comparing the poverty data for people since the 1960 census.

Current Population Survey
Because the questionnaires and data collection procedures differ, Census 2000 estimates of the number of people below the poverty level by various characteristics may differ from those reported in the March 2000 Current Population Survey. Please refer to www.census.gov/hhes/income/guidance.htmlfor more details.

Household poverty data
Poverty status is not defined for households - only for families and unrelated individuals. Because some data users need poverty data at the household level, we have provided a few matrices that show tallies of households by the poverty status of the householder. In these matrices, the householder's poverty status is computed exactly the same way as described above. Therefore, to determine whether or not a "household" was in poverty, anyone who is not related to the householder is ignored.

Example #1: Household #1 has six members - a married couple, Alice and Albert, with their 10-year-old nephew, Aaron, and another married couple, Brian and Beatrice, with their 6-year-old son, Ben. Alice is the householder. Brian, Beatrice, and Ben are not related to Alice.

Household member Relationship to Alice Income
Alice self (householder) $5,000
Albert spouse $40,000
Aaron related child $0
Brian unrelated individual $0
Beatrice unrelated individual $5,000
Ben unrelated individual $0

The total income of Alice's family is $45,000, and their poverty threshold is $13,410, since there are three people in the family, with one member under age 18. Their income is greater than their threshold, so they are not classified as poor. Their ratio of income to poverty is 3.36 ($45,000 divided by $13,410). Alice's income-to-poverty ratio is also 3.36, because everyone in the same family has the same poverty status.
Even though Brian, Beatrice and Ben would be classified as poor if they lived in their own household, the household is not classified as poor because the householder, Alice, is not poor, as was shown in the computation above.

Example #2: Household #2 consists of four adults, Claude, Danielle, Emily, and Francis, who are unrelated to each other and are living as housemates. Claude, who is age 30, is the householder.

Household member Relationship to Claude Income
Claude self (householder) $4,500
Danielle unrelated individual $82,000
Emily unrelated individual $28,000
Francis unrelated individual $40,000


Because Claude is under age 65 and is not living with any family members, his poverty threshold is $8,667. Since his income, $4,500, is less than his threshold, he is considered poor. His ratio of income to poverty is 0.52 ($4,500 divided by $8,667).
Household #2 would be classified as poor because its householder, Claude, is poor, even though the other household members (who are not related to Claude) are not in poverty.

Excerpt from: Social Explorer, U.S. Census Bureau; 2000 Census of Population and Housing, Summary File 3: Technical Documentation, 2002.
 
Family Type
A family includes a householder and one or more other people living in the same household who are related to the householder by birth, marriage, or adoption. All people in a household who are related to the householder are regarded as members of his or her family. A family household may contain people not related to the householder, but those people are not included as part of the householder's family in census tabulations. Thus, the number of family households is equal to the number of families, but family households may include more members than do families. A household can contain only one family for purposes of census tabulations. Not all households contain families since a household may be comprised of a group of unrelated people or of one person living alone.

Families are classified by type as either a "married-couple family" or "other family" according to the presence of a spouse. "Other family" is further broken out according to the sex of the householder. The data on family type are based on answers to questions on sex and relationship that were asked on a 100-percent basis.

Married-couple family
This category includes a family in which the householder and his or her spouse are enumerated as members of the same household.

Other family
Male householder, no wife present
This category includes a family with a male maintaining a household with no wife of the householder present.

Female householder, no husband present
This category includes a family with a female maintaining a household with no husband of the householder present.

Nonfamily household
This category includes a householder living alone or with nonrelatives only.

Average family size
A measure obtained by dividing the number of people in families by the total number of families (or family householders). In cases where this measure is tabulated by race or Hispanic origin, the race or Hispanic origin refers to that of the householder rather than to the race or Hispanic origin of each individual. Average family size is rounded to the nearest hundredth.

Excerpt from: Social Explorer, U.S. Census Bureau; 2000 Census of Population and Housing, Summary File 3: Technical Documentation, 2002.
 
Age
The data on age, which was asked of all people, were derived from answers to the long-form questionnaire Item 4 and short-form questionnaire Item 6. The age classification is based on the age of the person in complete years as of April 1, 2000. The age of the person usually was derived from their date of birth information. Their reported age was used only when date of birth information was unavailable.

Data on age are used to determine the applicability of some of the sample questions for a person and to classify other characteristics in census tabulations. Age data are needed to interpret most social and economic characteristics used to plan and examine many programs and policies. Therefore, age is tabulated by single years of age and by many different groupings, such as 5-year age groups.

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

Limitation of the data
The most general limitation for many decades has been the tendency of people to overreport ages or years of birth that end in zero or 5. This phenomenon is called "age heaping." In addition, the counts in the 1970 and 1980 censuses for people 100 years old and over were substantially overstated. So also were the counts of people 69 years old in 1970 and 79 years old in 1980. Improvements have been made since then in the questionnaire design and in the imputation procedures that have minimized these problems.

Review of detailed 1990 census information indicated that respondents tended to provide their age as of the date of completion of the questionnaire, not their age as of April 1, 1990. One reason this happened was that respondents were not specifically instructed to provide their age as of April 1, 1990. Another reason was that data collection efforts continued well past the census date. In addition, there may have been a tendency for respondents to round their age up if they were close to having a birthday. It is likely that approximately 10 percent of people in most age groups were actually 1 year younger. For most single years of age, the misstatements were largely offsetting. The problem is most pronounced at age zero because people lost to age 1 probably were not fully offset by the inclusion of babies born after April 1, 1990. Also, there may have been more rounding up to age 1 to avoid reporting age as zero years. (Age in complete months was not collected for infants under age 1.)

The reporting of age 1 year older than true age on April 1, 1990, is likely to have been greater in areas where the census data were collected later in calendar year 1990. The magnitude of this problem was much less in the 1960, 1970, and 1980 censuses where age was typically derived from respondent data on year of birth and quarter of birth.

These shortcomings were minimized in Census 2000 because age was usually calculated from exact date of birth and because respondents were specifically asked to provide their age as of April 1, 2000. (For more information on the design of the age question, see the section below that discusses "Comparability.")

Comparability
Age data have been collected in every census. For the first time since 1950, the 1990 data were not available by quarter year of age. This change was made so that coded information could be obtained for both age and year of birth. In 2000, each individual has both an age and an exact date of birth. In each census since 1940, the age of a person was assigned when it was not reported. In censuses before 1940, with the exception of 1880, people of unknown age were shown as a separate category. Since 1960, assignment of unknown age has been performed by a general procedure described as "imputation." The specific procedures for imputing age have been different in each census. (For more information on imputation, see "Accuracy of the Data.")

Related children
Related children include the sons and daughters of the householder (including natural-born, adopted, or stepchildren) and all other people under 18 years old, regardless of marital status, in the household, who are related to the householder, except the spouse of the householder. Foster children are not included since they are not related to the householder.