American Community Survey Five-Year Estimates

1. American Community Survey Five-Year Estimates New York State Fall Affiliate Meeting October 28, 2010 Arun Peter Lobo Population Division 1

2. Overview • Three major concerns with 2005-2009 ACS census tract data: • The use of 2000 Geography • Validity of data • Reliability of data

3. New York City 2010 Census Tracts 2000 – 2010 CT Changes

4. Validity of Age Data at the PUMA level • And what it says about tract-level data

5. 3701 3702 Bronx Other, NH 5.8% 3706 White, NH 14.5% 3704 Black, NH 31.2% Hispanic 48.4% 3707 3705 3703 3708 3709 3710 Bronx Public Use Microdata Areas (PUMAs)

6. Method: The Cohort Component (CC) Model • The basic building blocks in a CC model are age and sex “cohorts” in a given population. • The CC model applies birth, death, and migration rates to these age and sex cohorts to project them into the future.

7. Age/Sex Distributions for Bronx PUMA 3701:2005-07 ACS, and 2006 DCP Baseline and DCP Estimates

8. Bronx PUMA 3701: DCP Baseline and DCP Modified Age-Specific Migration Rates for Males, 2000-2006 + 5 per 1,000 -21 per 1,000

9. Age/Sex Distributions for Bronx PUMA 3701:2005-07 ACS and 2006 DCP Absolute Estimates 100 age/sex estimates: 27 significant differences 9

10. Males Females 2005-2007 ACS 2006 DCP Estimate 2006 Baseline M F* M* F* M F M F M* F M F M F M F M F M F Population 0 to 4 by Sex for Bronx PUMAs: Comparing 2005-2007 ACS Estimates to DCP Estimates *Difference between the ACS and DCP estimates is significant at the .10 level.

11. Age/Sex Distributions for Bronx County, New York:2000 Census, and 2005-07 ACS and 2006 and DCP Estimates 11

12. Bronx County: ACS and DCP Age-Specific Migration Rates for Females, 2000-2006 48 per 1,000 -82 per 1,000

13. Males Females 2005-2007 ACS 2006 DCP Estimate 2006 Baseline M F M F M* F* M F* M F M* F* M F M F M F* M F Population 65 and Over by Sex for Bronx PUMAs: Comparing 2005-2007 ACS Estimates to DCP Estimates 13 *Difference between the ACS and DCP estimates is significant at the .10 level.

14. Age/Sex Distributions for Bronx PUMA 3701:2005-07 ACS and 2006 DCP Percent Distributions 100 age/sex estimates: 41 significant differences 24 of the differences were 2 points or greater, including 10 that were 3 points or greater 14

15. Bronx Other, NH 5.8% White, NH 14.5% Black, NH 31.2% Hispanic 48.4% 3707 3703 Hispanic Diversity in Bronx PUMAs in 2000 Hispanics Puerto Rican 34% Poverty 43% Hispanics Puerto Rican 72% Poverty 17%

16. 3702 Bronx Other, NH 5.8% White, NH 14.5% Black, NH 31.2% Hispanic 48.4% 3708 Black Diversity in Bronx PUMAs in 2000 Black nonhispanics Foreign-born 42% Poverty 17% Black nonhispanics Foreign-born 21% Poverty 36%

17. Low Reliability of ACS Estimates at the Census Tract Level And a solution for some users

18. Initial Sample Final Interviews ACS Initial Sample and Final Response as a Percent of all Bronx Housing Units, 2001-2005 2.8% 1.5% % of Bronx Housing Units 2.2% 1.1% Housing Unit Average: 496,517 ACS SAMPLE 5 Year Initial Sample Total: 56,761 (11.4% of annual avg. housing units) 5 Year Final Response Total: 29,896 (6.0% of annual avg. housing units) 2000 CENSUS LONG FORM Final Response was 11.3% of housing units 2.2% 1.2% 2.2% 1.1% 2.1% 1.2%

19. 43 Demographic, Social, Economic, and Housing Variables Bronx Census Tracts and Neighborhoods, 2001-2005 ACS

20. Margins of Error • Standard Error (SE): Measures the variability of an estimate due to sampling. • Margin of Error (MOE) : Describes the precision of an estimate at a given level of confidence. For the ACS, since 90 percent confidence used, MOE= SE*1.645 • Say we estimate the number of carpenters to be 10,000, with an MOE of 1,000 persons. • If we had the patience and the dollars to create the same estimate of carpenters several thousand times from several thousand samples, 90% of the estimates of carpenters would be between 9,000and 11,000.

21. Coefficient of Variation • Coefficient of Variation (CV) : Standardized indicator of the reliability of an estimate. CV=SE/Estimate • Step 1 - Derive the standard error MOE= SE*1.645 SE = MOE/1.645 =1,000/1.645=608 • Step 2 - Express the SE as a percent of the estimate CV= SE/Estimate * 100 CV = 608/10,000 * 100, or 6.0 percent • Step 3 – Evaluate: Our rule of thumb is that a CV in excess of 15 percent warrants caution

22. Median Overall Coefficients of Variation for Bronx Census Tracts, 2000 Census and 2001-2005 ACS Ratio of ACS to Census = 1.8 1.6 1.5 27.4 26.8 21.1 17.9 16.6 Coefficient of Variation 11.5

23. Neighborhood Aggregates of Bronx Census Tracts

24. Median Overall Coefficients of Variation for Bronx Census Tracts and Neighborhoods, 2001-2005 ACS Ratio of Neighborhoods to Tracts = 0.36 0.31 0.33 32.9 26.8 21.6 Coefficient of Variation 10.9 8.4 7.7

25. How Can We Assist Users? • Important things to keep in mind: • What the ACS is and isn’t • What a 5 year estimate means • Area with abundant change • Explain measures that have a “look back” period • Depict Confidence Intervals pictorially • Resist establishing “hard and fast” rules • Distinguish the ACS from the decennial count Create a sense that there is a “cycle” at work

27. Developing an Interactive Relationship with the Census Bureau • Creation of a User Feedback Loop • Keep track of inquiries and develop practical strategies to respond • Identify knowledge gaps that need to be addressed through special efforts

28. WEB SITE WWW.NYC.GOV/PLANNING