|Data Dictionary:||ACS 2009 (3-Year Estimates)|
|Data Source:||U.S. Census Bureau|
Universe: Women 15 to 50 years
|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 -> Fertility|
The data on fertility were derived from Question 17 in 1999-2002, Question 18 in 2003-2007, question 23 in 2008, and question 24 in 2009. The question asked if the person had given birth in the past 12 months, and was asked of all women 15 to 50 years old regardless of marital status. From this question, we are able to determine geographies with high numbers of women with births and the characteristics of these women, such as age and marital status. When fertility was not reported, it was imputed according to the womans age and marital status and the possibility there was an infant in the household. Data are most frequently presented in terms of the aggregate number of women who had a birth in the past 12 months in the specified category, and in terms of the rate per 1,000 women.
The 1996-1998 American Community Survey collected data on children ever born. (See the section on "Children Ever Born" for more information.) In 1999, the American Community Survey began collecting data on children born in the last 12 months.
Limitation of the Data
Beginning in 2006, the population in group quarters (GQ) is included in the ACS. Some types of GQ populations may have fertility distributions that are different from the household population. The inclusion of the GQ population could therefore have a noticeable impact on the fertility distribution. This is particularly true for areas with a substantial GQ population.
The data on fertility can be compared to previous ACS years and to similar data collected in the Current Population Survey (CPS) and Survey of Income and Program Participation (SIPP), and from the National Center for Health Statistics. All of these surveys have slightly different ways of determining the reference period but generally show births occurring over a period of 12 months.