|Data Dictionary:||ACS 2007 -- 2009 (3-Year Estimates)|
|Data Source:||U.S. Census Bureau|
Universe: Workers 16 years and over
|ACS 2009-3yr Summary File: Technical Documentation -> Appendix A. Supplemental Documentation -> 2009 Subject Definitions -> Quality Measures -> 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.
|ACS 2009-3yr Summary File: Technical Documentation -> Appendix A. Supplemental Documentation -> 2009 Subject Definitions -> Population Variables -> Journey to Work -> Means of Transportation to Work -> Travel Time to Work|
The data on travel time to work were derived from answers to Question 34. This question was asked of people who indicated in Question 29 that they worked at some time during the reference week, and who reported in Question 31 that they worked outside their home. Travel time to work refers to the total number of minutes that it usually took the worker to get from home to work during the reference week. The elapsed time includes time spent waiting for public transportation, picking up passengers in carpools, and time spent in other activities related to getting to work. (See "Reference Week".)
|ACS 2009-3yr Summary File: Technical Documentation -> Appendix A. Supplemental Documentation -> 2009 Subject Definitions -> Population Variables -> Household -> Relationship to Householder -> Family Households|
A family consists of 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 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 tabulations. Not all households contain families since a household may be comprised of a group of unrelated people or of one person living alone - these are called nonfamily households. Families are classified by type as either a "married-couple family" or "other family" according to the sex of the householder and the presence of relatives. The data on family type are based on answers to questions on sex and relationship that were asked of all people.
- Married-Couple Family - A family in which the householder and his or her spouse are listed as members of the same household.
- Other Family: Male Householder, No Wife Present - A family with a male householder and no spouse of householder present.
- Female Householder, No Husband Present - A family with a female householder and no spouse of householder present.