1. American Community Survey (ACS) 1 Oregon State Data Center Meeting Portland State University April 14, 2009 1

2. Agenda ACS & the Decennial Census Census 2000 2010 Census Key Differences in the ACS ACS Data Releases ACS Survey Methodology ACS Multiyear Estimates ACS Data Products Accessing ACS Data Online 2

3. Census 2000 3

4. 44 ACS and the Decennial Census Census 2000 In 2000, the Census used two questionnaires 1. Short form (“counts”) Asked basic demographic and housing information, such as age, sex, race, how many people lived in the housing unit, and if the housing unit was owned or rented by the resident 2. Long form (“characteristics”) Collected the same information as the short form but also collected more in-depth information such as income, education, and language spoken at home Only a portion of the population - - called a sample - - received the long form (average of 1 in 6 nationwide)

5. 2010 Census 5

6. 66 ACS and the Decennial Census 2010 Census 2010 Census to focus on the “counts” (100%) data –All addresses receive the same Census (short) form ACS will collect the “characteristics” (sample) data –3,000,000 addresses in 2010 will receive the ACS survey in addition to the 2010 Census form –Short form questions are also asked on the ACS

7. Key Differences between the ACS and Census 2000 7

8. 88 ACS and the Decennial Census Key Differences Residency –ACS uses “two-month” rule –Decennial census based on concept of “usual residence” Employment –Both ACS and Decennial ask respondents if they worked for pay “last week” –ACS collects data year-round and produces an average of the data collected for the period 8

9. ACS and the Decennial Census Key Differences (continued) Income –Decennial census income data refer to the previous calendar year –ACS asks for income for the previous 12 months School enrollment –Decennial census asks if a person attended school “any time since February 1” –ACS asks if a person attended school during the “last 3 months”

10. Data Releases 10

11. 11 American Community Survey Data Releases Goal is to produce estimates comparable to the Census 2000 long form data –Estimates cover the same small areas (down to the block group level) as Census 2000 long form, but with smaller sample sizes Caveat: Smaller sample size = Reductions in reliability of estimates 11

12. 12 American Community Survey Data Releases ACS estimates are period estimates –Describe the average characteristics over a specified period –Contrast with point-in-time estimates that describe the characteristics of an area on a specific date ACS releases 1-year, 3-year, and 5-year estimates for geographic areas that meet specific population thresholds

13. 13 American Community Survey Data Releases: Schedule

14. Census Geographic Entities: Hierarchy 14

15. 15

16. Survey Methodology 16

17. 17 American Community Survey Methodology Sample includes about 250,000 addresses per month, or 3 million addresses each year, Group quarters populations included in the ACS since 2006 Data collected continuously throughout the year by three modes –Mail –Phone –Personal visit

18. 18 Caveats ACS data are estimates ACS data are not counts of the population or housing Population counts are produced from the decennial census –Counts are updated throughout the decade through the Population Estimates Program

19. 19 ACS Estimates: Period Estimates Period estimates describe the average characteristics over a specific time period Point-in-time estimates describe characteristics as of a specific date

20. 20 Sampling Error The uncertainty associated with an estimate that is based on data gathered from a sample of the population rather than the full population Margin of error (MOE) measures the precision of an estimate at a given level of confidence MOEs at the 90% confidence level for all published ACS estimates

21. 21 ACS Multiyear Estimates

22. 22 ACS Multiyear Estimates Definition A period estimate that encompasses more than one calendar year Period for ACS multiyear estimates is either 3 or 5 calendar years –First release for 3-year estimate is 2008 (for period 2005-2007) –First release for 5-year estimate is 2010 (for period 2005-2009)

23. 23 Constructing Multiyear Estimates Data are pooled across 36 or 60 months Data are weighted to produce estimates Estimates are controlled for age, sex, race, and Hispanic origin Multiyear estimates are not an average of 1-year estimates

24. 24 When to Use Multiyear Estimates No one-year estimate is available Margins of error for 1-year estimates are larger than required Analyzing data for small population groups

25. 25 Currency vs. Reliability CurrencyReliability 1-year estimates provide information based on the last year Larger sample sizes produce estimates that are more statistically reliable 3-year estimates provide information based on the last year and the 2 years before that 3-year estimates are based on 3 times as many sample cases as 1- year estimates 5-year estimates provide information based on the last year and the 4 years before that 5-year estimates are based on 5 times as many sample cases as 1- year estimates

26. 26 Reliability Note: Fictional data

27. 27 How to Label Multiyear Estimates Multiyear estimates do not represent any one year nor the midpoint of a period ACS estimates based on data collected from 2005-2007 should not be labeled “2006” or “2007” estimates Correct labeling for multiyear estimate: “The child poverty rate for the 2005-2007 period was X percent.”

28. 28 Inflation Adjustment Dollar-valued data items are inflation adjusted to the most recent year for the period Income, rent, home value, and energy costs Adjusted using inflation factors based on the Consumer Price Index (CPI) Adjustment designed to put the data into dollars with equal purchasing power

29. 29 Population Controls Estimates of housing units and people controlled to the population estimates derived from the Population Estimates Program Multiyear estimates controlled to the average of the individual year’s estimates for the period

30. 30 Population Thresholds for ACS Estimates Review 1-year estimates 3-year estimates 5-year estimates 65,000 + people XXX 20,000+ people XX Less than 20,000 people X

31. 31 Geographic Boundaries Multiyear estimates are based on geographic boundaries as of January 1 of the last year in the multiyear period Boundary Annexation Survey collects boundary changes Boundaries of other statistical areas will be updated every decade in conjunction with the decennial census

32. 32 Comparing Across Geographies Only compare the same type of estimate 1-year estimates to other 1-year estimates 3-year estimates to other 3-year estimates 5-year estimates to other 5-year estimates Same time period

33. 33 Counties in Kentucky, by Population Size Source: U.S. Census Bureau, American Community Survey Handbook for General Audiences Fulton Franklin Fayette

34. 34 Comparing Data in 2010 20092007-20092005-2009 Fayette CountyXXX Franklin CountyXX Fulton CountyX

35. 35 Comparing Across Time Periods Same geographic area –Use caution if geographic boundaries have changed over time –Easier to compare non-overlapping periods –Make comparisons using the same length time period

36. 36 Comparing ACS Data with Census 2000 Differences exist between ACS and Census 2000 Comparisons can be made for most population and housing subjects Crosswalk available –“Compare” –“Compare with Caution” –“Do Not Compare” http://www.census.gov/acs/www/UseData/compACS.htm

37. 37 Choosing the Estimates –1999-2001 vs. 2000-2002 –1999-2001 vs. 2001-2003 –1999-2001 vs. 2002-2004 –1999-2001 vs. 2003-2005 –2000-2002 vs. 2001-2003 –2000-2002 vs. 2002-2004 –2000-2002 vs. 2003-2005 –2001-2003 vs. 2002-2004 –2001-2003 vs. 2003-2005 –2002-2004 vs. 2003-2005 These estimates allow for ten comparisons:

38. 38 Determining Which Estimates to Use

39. 39 Summary on Multiyear Estimates Multiyear estimates are period estimates and should be interpreted and labeled as such Data users should consider the tradeoffs of currency versus reliability Comparisons between estimates of different geographies should be based on ACS data from the same time periods It is easier to compare estimates from non- overlapping periods

40. 40 ACS Data Products 40

41. 41 American Community Survey Data Products Profiles –Data Profiles –Narrative Profiles –Comparison Profiles –Selected Population Profiles Tables –Detailed Tables –Subject Tables –Ranking Tables –Geographic Comparison Tables Thematic Maps Public Use Microdata Sample (PUMS) Files

42. 42 Data Profiles Data Profile

43. 43 Narrative Profiles Narrative Profile

44. 44 Comparison Profiles 44 Comparison Profile

45. 45 Selected 45 Selected Population Profiles

46. 46 Selected Population Profiles Selected Population Profiles

47. 47 Detailed Tables Examples Sex by Age by Race and Hispanic Origin Means of Transportation to Work by Travel Time to Work Median Number of Rooms in Housing Units School Enrollment by Level of School Poverty Status in the past 12 Months by Sex and Age

48. 48 Data Source Universe Margin of Error Table Name Table Number Collapsed Version Detailed Tables

49. 49 Detailed Tables – Collapsed Version 49

50. 50 Detailed Table

51. 51 Detailed Tables for Quality Measures

52. 52 Subject Table List

53. 53 Subject Tables Subject Table

54. 54 Ranking Table

55. 55 Ranking Table

56. 56 Geographic Comparison Table 56 Geographic Comparison Table

57. 57 Thematic Map

58. 58 Public Use Microdata Sample (PUMS)

59. PUMS PUMS = Public Use Microdata Sample Includes a sample of untabulated records for individuals and housing units Provides access to custom tables that are not available through pretabulated ACS products Requires users to download data and analyze with statistical software, or access through DataFerrett Data users must calculate standard errors 59

60. Accessing ACS Data Online 60

61. Census Bureau Home Page http://www.census.gov 61

62. American FactFinder (AFF) Main Page http://factfinder.census.gov American FactFinder is the data access tool for: (1)Decennial Censuses, (2)American Community Survey, (3)Annual Population Estimates, and (4)Economic Censuses and Surveys. 62

63. American FactFinder Data Sets Main Page 63

64. American Community Survey Main Page http://www.census.gov/acs/www 64

66. 66 Linda Clark Information Services Specialist Seattle Regional Census Center (425) 908-3062 linda.clark@census.gov Questions?