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Data Dictionary: ACS 2007 (3-Year Estimates)
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Data Source: U.S. Census Bureau
Universe: Universe: Civilian employed population 16 years and Over
Relevant Documentation:
Excerpt from: Social Explorer; U.S. Census Bureau; 2005-2007 American Community Survey 3-Year Summary File: Technical Documentation.
  ACS 2007-3yr Summary File: Technical Documentation -> Appendix B. Subject Definitions -> Population Variables -> Industry, Occupation, and Class of Worker -> Industry
Industry
The data on industry were derived from answers to Questions 36 through 38. Written responses to the industry questions are coded using the industry classification system developed for Census 2000 and modified in 2002 and again in 2007. This system consists of 269 categories for employed people, including military, classified into 20 sectors. The modified 2007 census industry classification was developed from the 2007 North American Industry Classification System (NAICS) published by the Executive Office of the President, Office of Management and Budget. The NAICS was developed to increase comparability in industry definitions between the United States, Mexico, and Canada. It provides industry classifications that group establishments into industries based on the activities in which they are primarily engaged. The NAICS was created for establishment designations and provides detail about the smallest operating establishment, while the American Community Survey data are collected from households and differ in detail and nature from those obtained from establishment surveys. Because of potential disclosure issues, the census industry classification system, while defined in NAICS terms, cannot reflect the full detail for all categories. The industry category, "Public administration," is limited to regular government functions such as legislative, judicial, administrative, and regulatory activities. Other government organizations such as public schools, public hospitals, and bus lines are classified by industry according to the activity in which they are engaged.
Excerpt from: Social Explorer; U.S. Census Bureau; 2005-2007 American Community Survey 3-Year Summary File: Technical Documentation.
  ACS 2007-3yr Summary File: Technical Documentation -> Appendix B. Subject Definitions -> Population Variables -> Industry, Occupation, and Class of Worker -> Class of Worker
Class of Worker
The data on class of worker were derived from answers to Question 35. The information on class of worker refers to the same job as a respondent's industry and occupation and categorizes people according to the type of ownership of the employing organization. The class of worker categories are defined as follows:
Private wage and salary workers
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Includes people who worked for wages, salary, commission, tips, pay-in-kind, or piece rates for a private for-profit employer or a private not-for-profit, tax-exempt or charitable organization. Self-employed people whose business was incorporated are included with private wage and salary workers because they are paid employees of their own companies.
ACS tabulations present data separately for these subcategories: "Private for-profit wage and salary workers," "Private not-for-profit wage and salary workers," "Self-employed in own incorporated business workers," and "Own not incorporated business workers."
Government workers
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Includes people who were employees of any local, state, or federal governmental unit, regardless of the activity of the particular agency. For ACS tabulations, the data are presented separately for the three levels of government.
Employees of foreign governments, the United Nations, or other formal international organizations controlled by governments were classified as "federal government workers."
The class of worker government categories includes all government workers, though government workers may work in different industries. For example, people who work in a public elementary or secondary school are coded as local government class of workers.

Self-employed in own not incorporated business workers
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Includes people who worked for profit or fees in their own unincorporated business, profession, or trade, or who operated a farm.

Unpaid family workers
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Includes people who worked without pay in a business or on a farm operated by a relative.
Following the coding operation, a computer edit and allocation process excludes all responses that should not be included in the universe, and evaluates the consistency of the remaining responses. The codes for the three questions (industry, occupation, and class of worker) are then checked to ensure they are valid and consistent with the other codes returned for that respondent. Occasionally respondents supplied industry, occupation, or class of worker descriptions that were not sufficiently specific for precise classification, or they did not report on these questions at all. Certain types of incomplete entries were corrected using theAlphabetical Index of Industries and Occupations .
If one or more of the three codes was blank after the edit, a code was assigned from a donor respondent who was a "similar" person based on questions such as age, sex, education, and weeks worked. If all of the labor force and income data were blank, all of these economic questions were assigned from a "similar" person who had provided all the necessary data.
Excerpt from: Social Explorer; U.S. Census Bureau; 2005-2007 American Community Survey 3-Year Summary File: Technical Documentation.
  ACS 2007-3yr Summary File: Technical Documentation -> Appendix B. Subject Definitions -> Population Variables -> Employment Status -> Civilian Employed
Civilian Employed
This term is defined exactly the same as the term "employed" above.
Excerpt from: Social Explorer; U.S. Census Bureau; 2005-2007 American Community Survey 3-Year Summary File: Technical Documentation.
  ACS 2007-3yr Summary File: Technical Documentation -> Appendix B. Subject Definitions -> Population Variables -> Age
Age
The data on age were derived from answers to Question 2. The age classification is based on the age of the person in complete years at the time of interview. Both age and date of birth are used in combination to calculate the most accurate age at the time of the interview. Inconsistently reported and missing values are assigned or imputed based on the values of other variables for that person, from other people in the household, or from people in other households ("hot deck" imputation). Data on age are used to determine the applicability of other questions for a particular individual and to classify other characteristics in tabulations. Age data are needed to interpret most social and economic characteristics used to plan and analyze programs and policies. Therefore, age data are tabulated by many different age groupings, such as 5-year age groups.
Median Age
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The median age is the age that divides the population into two equal-size groups. Half of the population is older than the median age and half is younger. Median age is based on a standard distribution of the population by single years of age and is shown to the nearest tenth of a year. (See the sections on "Standard Distributions" and "Medians" under "Derived Measures.")
Age Dependency Ratio
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The age dependency ratio is derived by dividing the combined under-18 and 65-and-over populations by the 18-to-64 population and multiplying by 100.
Old-Age Dependency Ratio
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The old-age dependency ratio is derived by dividing the population 65 years and over by the 18-to-64 population and multiplying by 100.
Child Dependency Ratio
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The child dependency ratio is derived by dividing the population under 18 years by the 18-to-64 population, and multiplying by 100.
Limitation of the Data
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Caution should be taken when comparing population in age groups across time. The entire population continually ages into older age groups over time and babies fill in the youngest age group. Therefore, the population of a certain age is made up of a completely different group of people in 2000 and 2007. Since populations occasionally experience booms/increases and busts/decreases in births, deaths, or migration (for example, the postwar Baby Boom from 1946-1964), one should not necessarily expect that the population in an age group in Census 2000 should be similar in size or proportion to the population in the same age group in the 2007 ACS. For example, Baby Boomers were age 36 to 54 in Census 2000 while they were age 44 to 62 in the 2007 ACS. Therefore, the age group 55 to 59 would show a considerable increase in population when comparing Census 2000 data with the 2007 ACS data.
Beginning in 2006, the population in group quarters (GQ) is included in the ACS. Some types of GQ populations have age distributions that are very different from the household population. The inclusion of the GQ population could therefore have a noticeable impact on the age distribution. This is particularly true for areas with a substantial GQ population.
Question/Concept History
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The 1996-2002 American Community Survey question asked for month, day, and year of birth before age. Since 2003, the American Community Survey question asked for age, followed by month, day, and year of birth. In 2007, an additional instruction was provided with the age and date of birth question on the American Community Survey questionnaire to report babies as age 0 when the child was less than 1 year old. The addition of this instruction occurred after 2005 National Census Test results indicated increased accuracy of age reporting for babies less than one year old.