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.")

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."

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."

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.

The data on the Hispanic or Latino population, which was asked of all people, were derived from answers to long-form questionnaire Item 5, and short-form questionnaire Item 7. The terms "Spanish," "Hispanic origin," and "Latino" are used interchangeably. Some respondents identify with all three terms, while others may identify with only one of these three specific terms. Hispanics or Latinos who identify with the terms "Spanish," "Hispanic," or "Latino" are those who classify themselves in one of the specific Hispanic or Latino categories listed on the questionnaire - "Mexican," "Puerto Rican," or "Cuban" - as well as those who indicate that they are "other Spanish, Hispanic, or Latino." People who do not identify with one of the specific origins listed on the questionnaire but indicate that they are "other Spanish, Hispanic, or Latino" are those whose origins are from Spain, the Spanish-speaking countries of Central or South America, the Dominican Republic, or people identifying themselves generally as Spanish, Spanish-American, Hispanic, Hispano, Latino, and so on. All write-in responses to the "other Spanish/Hispanic/Latino" category were coded.

Origin can be viewed as the heritage, nationality group, lineage, or country of birth of the person or the person's parents or ancestors before their arrival in the United States. People who identify their origin as Spanish, Hispanic, or Latino may be of any race.

Some tabulations are shown by the origin of the householder. In all cases where the origin of households, families, or occupied housing units is classified as Spanish, Hispanic, or Latino, the origin of the householder is used. (For more information, see the discussion of householder under "Household Type and Relationship.")

If an individual could not provide a Hispanic origin response, their origin was assigned using specific rules of precedence of household relationship. For example, if origin was missing for a natural-born daughter in the household, then either the origin of the householder, another natural-born child, or the spouse of the householder was assigned. If Hispanic origin was not reported for anyone in the household, the origin of a householder in a previously processed household with the same race was assigned. This procedure is a variation of the general imputation procedures described in "Accuracy of the Data," and is similar to those used in 1990, except that for Census 2000, race and Spanish surnames were used to assist in assigning an origin. (For more information, see the "Comparability" section below.)