Data Dictionary: ACS 2008 (1-Year Estimates)
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Data Source: U.S. Census Bureau
Universe: Population 16 to 64 years
Relevant Documentation:
Excerpt from: Social Explorer; U.S. Census Bureau; American Community Survey 2008 Summary File: Technical Documentation.
 
Sex
The data on sex were derived from answers to Question 3. Individuals were asked to mark either "male" or "female" to indicate their sex. For most cases in which sex was not reported, the appropriate entry 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.
Sex Ratio
The sex ratio represents the balance between the male and female populations. Ratios above 100 indicate a larger male population, and ratios below 100 indicate a larger female population. This measure is derived by dividing the total number of males by the total number of females and then multiplying by 100. It is rounded to the nearest tenth.
Limitation of the data
Beginning in 2006, the population in group quarters (GQ) is included in the ACS. Some types of GQ populations have sex distributions that are very different from the household population. The inclusion of the GQ population could therefore have a noticeable impact on the sex distribution. This is particularly true for areas with a substantial GQ population.

The Census Bureau tested the changes introduced to the 2008 version of the sex question in the 2007 ACS Grid-Sequential Test (http://www.census.gov/acs/www/Downloads/ACS-MP-09_Grid-Sequential_Test_Final_Report.pdf). The results of this testing show that the changes may introduce an inconsistency in the data produced for this question as observed from the years 2007 to 2008.
Question/Concept History
Beginning in 2008, the layout of the sex question response categories was changed to a horizontal side-by-side layout from a vertically stacked layout on the mail paper ACS questionnaire.
Excerpt from: Social Explorer; U.S. Census Bureau; American Community Survey 2008 Summary File: Technical Documentation.
 
Disability Status
Using models of disability from the Institute of Medicine and the International Classification of Functioning, disability is defined as the restriction in participation that results from a lack of fit between the individual's functional limitations and the characteristics of the physical and social environment. So while the disability is not seen as intrinsic to the individual, the way to capture it in a survey is to measure components that make up the process. The American Community Survey identifies serious difficulty in four basic areas of functioning: vision, hearing, ambulation, and cognition. Described below, the ACS asks respondents about serious difficulty and the resulting data can be used individually or combined. The ACS also includes two questions to identify people with difficulties that might impact their ability to live independently. In the 2008 American Community Survey, there are three disability questions, two with subparts totaling six questions in all, as described below.
Limitation of the Data
The 2008 American Community Survey questions on disability represent a conceptual and empirical break from earlier years of the ACS. Hence, the Census Bureau does not recommend any comparisons to disability data from the 2007 ACS and earlier. For additional information on the differences between the 2008 ACS disability questions and prior ACS disability questions, see "2006 ACS Content Test Evaluation Report Covering Disability" (http://www.census.gov/acs/www/AdvMeth/content_test/P4_Disability.pdf).

The universe for most disability data tabulations is the civilian noninstitutionalized population. Some types of GQ populations have disability distributions that are different from the household population. The inclusion of the noninstitutionalized GQ population could therefore have a noticeable impact on the disability distribution. This is particularly true for areas with a substantial noninstitutionalized GQ population. For a discussion of the effect of group quarters data has on estimates of disability status, see "Disability Status and the Characteristics of People in Group Quarters: A Brief Analysis of Disability Prevalence among the Civilian Noninstitutionalized and Total Populations in the American Community Survey" (http://www.census.gov/hhes/www/disability/GQdisability.pdf).
Hearing and Vision Limitations
The data on hearing and vision limitations were derived from answers to Questions 16a and 16b. Question 16a asked respondents if they were "deaf or ... [had] serious difficulty hearing." Question 16b asked if respondents were "blind or ... [had] serious difficulty seeing even when wearing glasses." Respondents were instructed to mark "yes" or "no" for each question. Question 16a is labeled as "Hearing difficulty" and Question 16b as "Vision difficulty" for some of the disability data products such as the ACS Detailed Tables.
Limitation of the Data
The Census Bureau does not recommend trend analysis using the 2008 data with years prior to 2008 due to the questionnaire change.
Question/Concept History
The 2008 American Community Survey marks a break in the series of disability data. In the 1999 - 2007 American Community Surveys, hearing and vision limitations were captured with one question, referred in data products as "Sensory disability." As such, parsing out which limitation respondents identified with was impossible. In addition, research has showed that combining the two new measures to replicate a similar measure as the old one proved not comparable. For additional information on the differences between the 2008 ACS disability questions and prior ACS disability questions, see "2006 ACS Content Test Evaluation Report Covering Disability" (http://www.census.gov/acs/www/AdvMeth/content_test/P4_Disability.pdf).
Limitations in Cognitive Functioning
The data on cognitive functioning were derived from answers to Question 17a, which was asked of people 5 years old and over. The question asked respondents if due to physical, mental, or emotional condition, they had "serious difficulty concentrating, remembering, or making decisions." Respondents were instructed to mark "yes" or "no." Question 17a is labeled as "Cognitive difficulty" for some disability data products such as the ACS Detailed Tables.
Limitation of the Data
The Census Bureau does not recommend trend analysis using the 2008 data with years prior to 2008 due to the questionnaire change.
Question/Concept History
The 2008 American Community Survey marks a break in the series of disability data. In prior American Community Surveys, a similar question about difficulty "learning, remembering, and concentrating" was asked. However, the change in activities on which cognitive limitations are based suggest that the 2008 measure is not comparable with the "Mental disability" estimates from prior years. For additional information on the differences between the 2008 ACS disability questions and prior ACS disability questions, see "2006 ACS Content Test Evaluation Report Covering Disability" (http://www.census.gov/acs/www/AdvMeth/content_test/P4_Disability.pdf).
Ambulatory Limitations
The data on ambulatory functioning were derived from answers to Question 17b, which was asked of people 5 years old and over. The question asked respondents if they had "serious difficulty walking or climbing stairs." Respondents were instructed to mark "yes" or "no." Question 17b is labeled as "Ambulatory difficulty" for some disability data products such as the ACS Detailed Tables.
Limitation of the Data
The Census Bureau does not recommend trend analysis using the 2008 data with years prior to 2008 due to the questionnaire change.
Question/Concept History
The 2008 American Community Survey marks a break in the series of disability data. In prior American Community Surveys, a similar question about "conditions that limit one or more basic physical activities such as walking, climbing stairs, reaching, lifting, or carrying" was asked However, the changes to the wording and tailoring of the list of activities on which the limitation is based suggest that the 2008 measure is not comparable with the "Physical disability" estimates from prior years. For additional information on the differences between the 2008 ACS disability questions and prior ACS disability questions, see "2006 ACS Content Test Evaluation Report Covering Disability" (http://www.census.gov/acs/www/AdvMeth/content_test/P4_Disability.pdf).
Self-Care Limitations
The data on self-care limitations were derived from answers to Question 17c, which was asked of people 5 years and over. The question asked respondents if they had "difficulty dressing or bathing." Respondents were instructed to mark yes or no. Question 17c is labeled as "Self-care difficulty" for some disability data products such as the ACS Detailed Tables.
Limitation of the Data
The Census Bureau does not recommend trend analysis using the 2008 data with years prior to 2008 due to the questionnaire change.
Question/Concept History
The 2008 American Community Survey marks a break in the series of disability data. In prior American Community Surveys, a similar question about difficulty "dressing, bathing, or getting around inside the home" was asked. However, the changes to the wording and tailoring of the list of activities on which the limitation is based suggest that the 2008 measure is not comparable with the "Self-care disability" estimates from prior years. For additional information on the differences between the 2008 ACS disability questions and prior ACS disability questions, see "2006 ACS Content Test Evaluation Report Covering Disability" (http://www.census.gov/acs/www/AdvMeth/content_test/P4_Disability.pdf).
Independent Living Limitations
The data on independent living limitations were derived from answers to Question 18, asked of people 15 years and over. The question asked respondents if due to a physical, mental, or emotional condition, they had difficulty "doing errands alone such as visiting a doctors office or shopping." Respondents were instructed to mark "yes" or "no." Question 18 is labeled as "Independent living difficulty" for some disability products such as the ACS Detailed Tables.
Limitation of the Data
The Census Bureau does not recommend trend analysis using the 2008 data with years prior to 2008 due to the questionnaire change.
Question/Concept History
The 2008 American Community Survey marks a break in the series of disability data. In prior American Community Surveys, a similar question about difficulty "going outside the home alone to shop or visit a doctor's office" was asked. However, the changes to the wording of the question suggest that the 2008 measure is not comparable with the "Going-outside-home disability" estimates from prior years. For additional information on the differences between the 2008 ACS disability questions and prior ACS disability questions, see "2006 ACS Content Test Evaluation Report Covering Disability" (http://www.census.gov/acs/www/AdvMeth/content_test/P4_Disability.pdf).
Disability Status
The Census Bureau uses the six disability questions above to determine an individuals disability status in some of its data products such as in the ACS Detailed Tables and the Disability Profile. People under 5 years were classified as having a disability if they were reported to have either a hearing or vision difficulty. People aged 5 to 14 were classified as having a disability if they were reported to have any one of the five limitations: hearing difficulty, vision difficulty, cognitive difficulty, ambulatory difficulty, or self-care difficulty. People aged15 and over were classified as having a disability if they reported any one of the six limitations described above.
Limitation of the Data
The Census Bureau does not recommend trend analysis using the 2008 data with years prior to 2008 due to the 2008 questionnaire change. For information on the differences between the 2008 ACS disability questions and prior ACS disability questions, see "2006 ACS Content Test Evaluation Report Covering Disability" (http://www.census.gov/acs/www/AdvMeth/content_test/P4_Disability.pdf).
Excerpt from: Social Explorer; U.S. Census Bureau; American Community Survey 2008 Summary File: Technical Documentation.
 
Work Status in the Past 12 Months
The data on work status in the past 12 months were derived from answers to Question 37. People 16 years old and over who worked 1 or more weeks according to the criteria described below are classified as "Worked in the past 12 months." All other people 16 years old and over are classified as "Did not work in the past 12 months."
Excerpt from: Social Explorer; U.S. Census Bureau; American Community Survey 2008 Summary File: Technical Documentation.
 
Usual Hours Worked Per Week Worked in the Past 12 Months
The data on usual hours worked per week worked in the past 12 months were derived from answers to Question 39. This question was asked of people 16 years old and over who indicated that they worked during the past 12 months.

The data pertain to the number of hours a person usually worked during the weeks worked in the past 12 months. The respondent was to report the number of hours worked per week in the majority of the weeks he or she worked in the past 12 months. If the hours worked per week varied considerably during the past 12 months, the respondent was to report an approximate average of the hours worked per week.

People 16 years old and over who reported that they usually worked 35 or more hours each week during the weeks they worked are classified as "Usually worked full time;" people who reported that they usually worked 1 to 34 hours are classified as "Usually worked part time."
Excerpt from: Social Explorer; U.S. Census Bureau; American Community Survey 2008 Summary File: Technical Documentation.
 
Weeks Worked in the Past 12 Months
The data on weeks worked in the past 12 months were derived from responses to Question 38, which was asked of people 16 years old and over who indicated that they worked during the past 12 months. The data pertain to the number of weeks during the past 12 months in which a person did any work for pay or profit (including paid vacation and paid sick leave) or worked without pay on a family farm or in a family business. Weeks of active service in the Armed Forces are also included.
Excerpt from: Social Explorer; U.S. Census Bureau; American Community Survey 2008 Summary File: Technical Documentation.
 
Age
The data on age were derived from answers to Question 4. 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
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
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
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
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
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 2008. 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 2008 ACS. For example, Baby Boomers were age 36 to 54 in Census 2000 while they were age 44 to 62 in the 2008 ACS. Therefore, the age group 55 to 59 would show a considerable increase in population when comparing Census 2000 data with the 2008 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
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 2008, 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.