Data Dictionary: ACS 2008 (1-Year Estimates)
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Data Source: U.S. Census Bureau
Table: B99181. Imputation Of Disability Items For The Civilian Noninstitutionalized Population [3]
Universe: Universe: Civilian noninstitutionalized population
Table Details
B99181. Imputation Of Disability Items For The Civilian Noninstitutionalized Population
Universe: Universe: Civilian noninstitutionalized population
Variable Label
B99181001
B99181002
B99181003
Relevant Documentation:
Excerpt from: Social Explorer; U.S. Census Bureau; American Community Survey 2008 Summary File: Technical Documentation.
 
Imputation Rates
Missing data for a particular question or item is called item nonresponse. It occurs when a respondent fails to provide an answer to a required item. The ACS also considers invalid answers as item nonresponse. The Census Bureau uses imputation methods that either use rules to determine acceptable answers or use answers from similar housing units or people who provided the item information. One type of imputation, allocation, involves using statistical procedures, such as within-household or nearest neighbor matrices populated by donors, to impute for missing values.
Overall Person Characteristic Imputation Rate
This rate is calculated by adding together the weighted number of allocated items across a set of person characteristics, and dividing by the total weighted number of responses across the same set of characteristics.
Overall Housing Characteristic Imputation Rate
This rate is calculated by adding together the weighted number of allocated items across a set of household and housing unit characteristics, and dividing by the total weighted number of responses across the same set of characteristics. These rates give an overall picture of the rate of item nonresponse for a geographic area.

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).