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American Community Survey

Idaho State Data CenterBoise

September 7, 2005

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What is the American Community Survey?

• A large, continuous demographic survey– Produces annual and multi-year estimates

of the characteristics of the population and housing

– Produces characteristics, not a population count– Produces information for small areas including

tracts, block groups and population subgroups - updated every year

– Key component of reengineered 2010 census

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What is the American Community Survey?

A program to provide annual and multi-year data for communities:– Age, gender, race/ethnicity– Families, children, elderly– Income, poverty– Work, unemployment– Housing– Education

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Effects of the American Community Survey (ACS)

on the 2010 Census• Eliminate long-form• Conduct a short form only census• Better knowledge of local areas• Ongoing contacts with local governments• Cost savings

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How will the American Community Survey help your

community?• Establish community goals• Compare your community with others• Identify community problems and solutions• Measure and publicize program results• Increase government accountability• Ensure fair funding distribution• Create community-specific programs• Locate facilities and programs

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Expansion to Full ACS Sample• Testing and development: 1996-2004• Full expansion began in 2005• Group quarters delayed until 2006 • Annual national sample of about 3 million

addresses• Provide profiles every year for communities of

65,000 or more• Provide 3- to 5-year cumulations for

communities of less than 65,000 population

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American Community Survey Data Release Timetable

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Comparing ACS with the Decennial Census Sample

• How do the samples compare?

• How does data collection compare?

• What is the impact on the data?

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How do the samples compare?

Similarities• Systematic samples of MAF (Master Address

File) addresses• Differential sampling rates for areas based on

population size

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Sampling Rates

Governmental Unit Size:

Number of Occupied

Housing Units

Census 2000

Sampling Rates

ACS 5-year

Sampling Rates

0 - 200 50.0% 50.0%

201 - 800 50.0% ~35.0%

801 - 1200 25.0% ~17.5%

1201 - 2000 16.7% ~12.0%

Over 2000 12.5% ~8.5%

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How do the samples compare?

Differences – ACS Sample Design• Initial sampling rate

– about 2.5% each year– about 12.5% over 5-year period

• Results in an initial sample of about – 250,000 addresses each month– 3 million addresses each year– 15 million addresses over 5-year period

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How do the samples compare?

Differences• ACS samples every year and spreads sample

over 12 months; census samples once a decade and uses the entire sample at the same time

• ACS subsamples for personal visit follow-up; court ruled against census subsampling

• Census sample estimates based on about 18 million housing units; ACS 5 year estimates based on about 11 million housing units

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How does data collection compare?

Similarities• Primary method is self-response to a paper

questionnaire• Content is the same

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How does data collection compare?

ACS data collection procedures:• Mail• Telephone• Personal visits

• Use a current residence rule

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How does data collection compare?

Differences• ACS nonresponse follow-up uses computer-

assisted telephone and computer-assisted personal interviews; past censuses have used only paper questionnaires

• ACS data collected only from household members; census data often collected from neighbors

• ACS interviews conducted by experienced and well-supervised staff; census enumerations conducted by inexperienced temporary workforce

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What is the impact on the data?

• ACS estimates have higher sampling error – measures are released for each estimate and

shown as 90% confidence limits or margins of error in every table

• Similar sampling error measures for census long form sample estimates have not been provided

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What is the impact on the data?

• ACS estimates have lower potential nonsampling error – Unit nonresponse: no data for a case– Item nonresponse: data missing for an item

• These and other measures are released on ACS’s Quality Measures website

www.census.gov/acs/www/UseData/sse/index.htm

1811

Unit Nonresponse

97.7--2002

96.7--2003

96.7--2001

95.191.22000

ACSCensus 2000 Sample

Response Rates (100-unit nr rate)

Unit Response

1912

Item Nonresponse

7.114.9Housing items - Followup

5.911.5Housing items - Mail

4.512.9Population items - Followup

8.18.7Population items - Mail

6.610.4All modes/ items

2000

ACS

Census 2000

Sample

Summary Allocation Rates(amount of data missing from

interviews)

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Multi-year Estimation

• Most multi-year estimates are generated by computing an average based on combining each years’ estimates

• Estimates are computed using the geography in place as of the most recent year of the period

• Dollar valued data items are inflation adjusted to most recent year of the period

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Multi-year Estimation: Medians

• Medians are produced using combined data records from all years, not by averaging each year’s median

• A 3-year median household income estimate is determined by combining the household records from the 3 years into one data set and determining the median from this combined distribution

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Multi-year Estimates

• Example– Item with year-to-year increases and decreases

• Overview only

• Focus is on the timing and creation of 3-year and 5-year data products

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Multi-year Estimates

Example 2: Item with year-to-year increases and decreases (Homeownership rates)

61.5%

55.6%

40.0%

44.3%

66.7%

52.0%

0%

10%

20%

30%

40%

50%

60%

70%

2005 2006 2007 2008 2009 2010

Year

Perc

en

t

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Example 1: Percent Foreign Born Population Areas with 65,000+ population

2005 2006 2007 2008 2009 2010

Single-year estimates 20.0 21.2 23.3 28.6 32.6 35.1

3-year estimates (2005 – 2007) 21.5

3-year estimates (2006 – 2008) 24.8

3-year estimates (2007 – 2009) 28.6

5-year estimates (2005 – 2009) 25.9

3-year estimates (2008 – 2010) 32.2

5-year estimates (2006 – 2010) 28.9

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Example 1: Percent Foreign Born Population Areas with population between 20,000 and 65,000

2005 2006 2007 2008 2009 2010

3-year estimates (2005 – 2007) 21.5

3-year estimates (2006 – 2008) 24.8

3-year estimates (2007 – 2009) 28.6

5-year estimates (2005 – 2009) 25.9

3-year estimates (2008 – 2010) 32.2

5-year estimates (2006 – 2010) 28.9

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Example 1: Percent Foreign Born Population Areas with less than 20,000 population

2005 2006 2007 2008 2009 2010

5-year estimates (2005 – 2009) 25.9

5-year estimates (2006 – 2010) 28.9

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ACS Data Products• Data Profiles• Multi-Year Profiles• Narrative Profiles • Expanded Ranking Tables• Redesigned and expanded Detailed Tables/Base

Tables• Public Use Microdata Sample Files (PUMS)• New: Subject Tables• New: Selected Population Profiles• New: Thematic Maps

ACS Data Products American FactFinder

http://factfinder.census.gov

American FactFinder

http://factfinder.census.gov

ACS Data Products

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Data Profiles

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Narrative Profile

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Multi-Year Profiles

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Ranking Tables

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Ranking Table(without statistical significance)

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Ranking Table (with statistical significance)

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Ranking Table (chart)

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Thematic Map

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Subject Table

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Selected Population Profile

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Detailed Table/Base Table

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2004 ACS Products by Geography Type

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Outreach and Education Materials

• State and local handbook• National and community organizations

handbook• Congressional toolkit• American Indian/Alaska Native toolkit• ACS Data User Guide (Fall 2005)

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Information about the American Community Survey

www.census.gov/acs/wwwwww.census.gov/acs/www

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Guide to the ACS Data Products

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For More Information

E-mail us at: cmo.acs@census.govE-mail us at: cmo.acs@census.gov

American Community Survey Web site

(www.census.gov/acs/www)

American Community Survey Web site

(www.census.gov/acs/www)Call us at: 1-888-456-7215Call us at: 1-888-456-7215

Subscribe to the ACS AlertSubscribe to the ACS Alert

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U. S. Census BureauSeattle Regional OfficePartnership and Data Services

Cam McIntosh, Information Specialist

U.S. Census Bureau

700 Fifth Avenue, Suite 5100

Seattle, WA 98104

cam.mcintosh@census.gov

800-233-3308

206-553-5836