The American Community Survey: The Census Bureau’s new annual survey of America

1. The American Community Survey:The Census Bureau’s new annual survey of America Will “Chip” Sawyer Vermont State Data Center

2. Background on the ACS • An ongoing year-round sample survey of ~3 mil. households • and a sample of group quarters • In Development since late 1990’s • Provides annual data releases • Nationwide since 2005 • Meant to “replace” the decennial “long form.” • income, disability, employment, education, ancestry, cost and condition of housing, etc.

3. Background on the ACS • Display Characteristics of the Population • Not Head Counts • ACS data are controlled to county level Census Population Estimates

4. Key Differences from Decennial “Long Form” Data are Period Estimates, not point-in-time 12 months, 36 months, or 60 months. or 1-year, 3-year and 5-year. Margins of Error accompany the data ACS data are actually ranges ACS Residence Rule is different from decennial Census “More than 2 months” vs. “most of the time” Some tables suppressed or collapsed Reasons: reliability and confidentiality 4

5. Changes: The American Community Survey What is a Period Estimate? An estimate that describes the average characteristics of an area over a specific time period. The period for ACS 1-year estimates is the 12 months that make up the calendar year. A 5-year ACS estimate means that all the data collected for 60 months (e.g., January 2005 through December 2009) are averaged to come up with one estimate. Multiyear estimates do not represent any one year or the midpoint of a period. Inflation is controlled to the final year of the estimate.

6. Period Estimates and Sample Size Combine years to build up the sample size From “2008 ACS Accuracy of the Data (US)”at http://www.census.gov/acs/www/UseData/Accuracy/Accuracy1.htm

7. ACS Release Schedule 7

8. Nebraska ACS Data • Thanks to Jerry Deichert for data • Omaha city was an ACS test site: 1997-2004 • Can examine 1, 3, 5-year data

13. ACS: Multi-Year Estimates Only two values truly independent of each other

14. ACS: Margins of Error • Were always there... • But ACS puts them front and center • Need to be displayed and used from now on • Help you to keep from interpreting small or nonexistent differences as important • i.e. two figures within each others’ margins of error probably aren’t statistically different • whether you’re comparing in time or space • Set at a 90% Confidence Interval

15. ACS: Margins of Error • So... • Actual 2008 VT median age is 41.2 to 41.8 • that’s the confidence interval

16. People Moving to North Dakota Within the Past Year by State of Origin: 2006 ACS Displaying Margins of Error

17. ACS: Residence Rule • What determines WHERE the Census counts you and your household • Decennial Census: “most of the time” • Considered to be a 6+ month residency rule • ACS: > 2 month residency rule • So... • Decennial Census counts primary residents • ACS likely will mix seasonal and primary

18. Decennial Census Residence Rule • “Most of the time” • Often referred to as the 6+ month rule

19. ACS Residence Rule

20. Suppression • Due to reasons of reliability / confidentiality, some tables or table items for a town may be suppressed and not released at all. • Census Bureau does not plan to suppress 5-year data.

21. Collapsing Tables • 2008 ACS – Means of Transportation to Work Table B08301 Table C08301 • Only the collapsed table is available for Chittenden County, VT

22. Accessing ACS Data • American FactFinder • factfinder.census.gov

23. Accessing ACS Data Also: Ranking tables with statistical significance ACS 2008: State Poverty Rate Rankings

24. Tools for Using ACS Data • Spreadsheet to Calculate ACS Margins of Error and Statistical Significance • Excel file created by NY SDC • Available at SDC Clearinghouse website • ACS Compass Products • 12 handbooks and presentations • Available at ACS website

25. The ACS Website http://www.census.gov/acs