Using ACS and Census 2010 in Communities and Neighborhoods: Guidelines and Tools POPULATION REFERENCE BUREAU | PRESENTATION BY MARK MATHER

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

© 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


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


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)


Data Overload?2000 State counts2001 C2SS PL 94-171 SF12002 SS01 SF2 SF32003 ACS 1-year SF42004 ACS 1-year2005 ACS 1-year2006 ACS 1-year2007 ACS 1-year2008 ACS 1-year ACS 3-year2009 ACS 1-year ACS 3-year2010 ACS 1-year ACS 5-year State counts2011 ACS 1-year ACS 3-year ACS 5-year PL 94-171 SF1


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


U.S. Population Trends, 1990-2010

Source: U.S. Census Bureau.

220,000

230,000

240,000

250,000

260,000

270,000

280,000

290,000

300,000

310,000

320,000

1990 1992 1994 1996 1998 2000 2002 2004 2006 2008 2010

U.S. population, in thousands

Census 2000

Census 2010?


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


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)


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


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


Guidelines for Making Comparisons Between Data Sources

Census 2000

Census 2010

2005 ACS

2006 ACS

2007 ACS

2008 ACS

2009 ACS

2010 ACS

2005-2007 ACS

2006-2008 ACS

2007-2009 ACS

2008-2010 ACS

2005-2009 ACS

2006-2010 ACS

Census 2000 --Census 2010 -- --2005 ACS -- -- --2006 ACS -- -- -- --2007 ACS -- -- -- -- --2008 ACS -- -- -- -- -- --2009 ACS -- -- -- -- -- -- --2010 ACS -- -- -- -- -- -- -- --2005-2007 ACS -- -- -- -- -- -- -- -- --2006-2008 ACS -- -- -- -- -- -- -- -- -- --2007-2009 ACS -- -- -- -- -- -- -- -- -- -- --2008-2010 ACS -- -- -- -- -- -- -- -- -- -- -- --2005-2009 ACS -- -- -- -- -- -- -- -- -- -- -- -- --2006-2010 ACS -- -- -- -- -- -- -- -- -- -- -- -- -- --

CompareCompare with cautionDo not compare


Accuracy of ACS Estimates (Sampling Error)

Census 2000 ACS 5-Year

Initial Addresses

18 million 14.5 million

Final interviews

16.4 million 10 million

HH Sampling Rate

1-in-6 1-in-9


14

Preliminary Coefficients of Variation for Tract-Level Poverty, 2005-2009

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

0 - 0-400 400-1000 - 1001-2000 2001-4000 - 4001-6000 6001+

CV

Size of Tract (Occupied Housing Units) Source: 2005 – 2009 ACS 5-year Data

Distribution %

Coefficient of variation

Source: Alfredo Navarro, U.S. Census Bureau, Presentation at APDU 2010 Annual Conference, Washington DC, Sept. 21, 2010.


15

Hypothetical Confidence Intervals For Tract-Level Poverty Rates, 2005-2009

ScenarioPoverty

RateCoefficient of Variation

Confidence Interval

Best Case 14 0.2 (9.4 - 18.6)Typical Case 14 0.3 (7.1 - 20.9)Worst Case 14 0.4 (4.8 - 23.2)Note: Data represent a typical tract with between 1,000-2,000 occupied housing units.


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


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


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


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


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!








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Using ACS and Census 2010 in Communities and Neighborhoods: Guidelines and Tools POPULATION REFERENCE BUREAU | PRESENTATION BY MARK MATHER