1. Using ACS and Census 2010 in Communities and Neighborhoods: Guidelines and Tools POPULATION REFERENCE BUREAU | www.prb.org PRESENTATION BY MARK MATHER (Population Reference Bureau) National Neighborhood Indicator Partnership Meeting October 2010

2. © 2010 Population Reference Bureau. All rights reserved. www.prb.org Focus of Presentation New data from the ACS and 2010 Census: What’s coming out and when? Issues around data accuracy and comparability Some practical guidelines for working with ACS data A new online tutorial for ACS data users

3. © 2010 Population Reference Bureau. All rights reserved. www.prb.org Timetable for ACS and Census 2010 April 1, 2010:-Census day Sept. 28, 2010: -ACS 2009 (1-year) Dec. 2010: -ACS 2005-2009 (5-year) -Census 2010 state counts

4. © 2010 Population Reference Bureau. All rights reserved. www.prb.org Timetable for ACS and Census 2010 (continued) Jan-Feb 2011: -ACS 2007-2009 (3-Year) Feb-March 2011:-Census 2010 PL 94-171 June-August 2011:-Census 2010 SF1 Fall-Winter 2011:-ACS 2010 (1-Year) -ACS 2008-2010 (3-Year) -ACS 2006-2010 (5-Year)

5. © 2010 Population Reference Bureau. All rights reserved. www.prb.org Data Overload?

6. © 2010 Population Reference Bureau. All rights reserved. www.prb.org Accuracy of ACS Estimates (Nonsampling Error) ACS population and housing totals are controlled to official population estimates: National, state, and county estimates by age, sex, race, and Hispanic origin Estimates are only as accurate as the decennial census counts on which they are based Estimates become less accurate over the decade

7. © 2010 Population Reference Bureau. All rights reserved. www.prb.org U.S. Population Trends, 1990-2010 Source: U.S. Census Bureau.

8. © 2010 Population Reference Bureau. All rights reserved. www.prb.org A Low Census Count in 2010? Will we pay the price for a high count in 2000? Expanded efforts to reduce duplicate records Declining immigration levels Potentially lower participation rates of immigrants in census

9. © 2010 Population Reference Bureau. All rights reserved. www.prb.org Implications for ACS Comparisons 2009 ACS 2009 ACS estimates controlled to Census 2000 (or population estimates based on Census 2000) Numbers may be inconsistent with Census 2010 2010 ACS estimates 2010 ACS estimates controlled to Census 2010 Numbers may be inconsistent with previous ACS estimates Counts are more likely to cause problems than characteristics (percents)

10. © 2010 Population Reference Bureau. All rights reserved. www.prb.org Other Considerations in Working with 5-Year ACS Data Use 2005-2009 ACS to look back Compare with Census 2000 Same geographic boundaries / population controls Use 2006-2010 ACS as the starting point to look forward Replacement for Census 2010 long form In Census 2010 geographies Includes Census 2010 population controls

11. © 2010 Population Reference Bureau. All rights reserved. www.prb.org Other Considerations in Making Comparisons Use caution in making comparisons with 2005 and earlier ACS, which excluded group quarters When comparing ACS estimates, use the same period length for each estimate Use caution in comparing multiyear estimates with overlapping years

12. © 2010 Population Reference Bureau. All rights reserved. www.prb.org Guidelines for Making Comparisons Between Data Sources

13. © 2010 Population Reference Bureau. All rights reserved. www.prb.org Accuracy of ACS Estimates (Sampling Error)

14. © 2010 Population Reference Bureau. All rights reserved. www.prb.org 14 Preliminary Coefficients of Variation for Tract- Level Poverty, 2005-2009 Coefficient of variation Source: Alfredo Navarro, U.S. Census Bureau, Presentation at APDU 2010 Annual Conference, Washington DC, Sept. 21, 2010.

15. © 2010 Population Reference Bureau. All rights reserved. www.prb.org 15 Hypothetical Confidence Intervals For Tract- Level Poverty Rates, 2005-2009

16. © 2010 Population Reference Bureau. All rights reserved. www.prb.org Options for Dealing with Small Numbers Ignore the potential error (not recommended) Present measures of reliability (MOEs are best for nontechnical audiences) Suppress unreliable estimates Aggregate data across geographic areas

17. © 2010 Population Reference Bureau. All rights reserved. www.prb.org Accessing 5-Year ACS Data American FactFinder Data available down to tract level No table restrictions based on reliability Selected Population Profiles not available Consider using ACS Summary Files as alternative source Includes all Detailed Tables in one place Only source for block-group level data (~300 tables) Need SAS / SPSS / Powerful PC or Server

18. © 2010 Population Reference Bureau. All rights reserved. www.prb.org Potential Improvements to ACS Increase in ACS sample size Improved sampling techniques to reduce error for small areas Improved population controls for small geographic areas

19. © 2010 Population Reference Bureau. All rights reserved. www.prb.org Final Thoughts The ACS has its limitations but it’s all that we have and has a lot of potential Continued funding is critical for tracking social and economic change We need to use the ACS data and advocate for it’s continuation and expansion: Larger sample size

20. © 2010 Population Reference Bureau. All rights reserved. www.prb.org Two New Online Tutorials U.S. Census Bureau E-Tutorial (http://www.census.gov/acs/www/guidance_for_data_users/e_tutorial/) ACS basics How to access data PRB Online Tutorial (http://www.icadmedia.com/PopRefBureau/intro_basics.html) ACS basics Issues around multiyear estimates, making comparisons, differences from Census 2000 How to access data Feedback wanted!

21. © 2010 Population Reference Bureau. All rights reserved. www.prb.org Two New Online Tutorials

22. © 2010 Population Reference Bureau. All rights reserved. www.prb.org Two New Online Tutorials

23. © 2010 Population Reference Bureau. All rights reserved. www.prb.org Two New Online Tutorials

24. © 2010 Population Reference Bureau. All rights reserved. www.prb.org For More Information… Mark Mather 202-939-5433 mmather@prb.org