introduction to the public use microdata sample (pums) file from the american community survey...

Introduction to the Public Use Microdata Sample

(PUMS) File from the American Community Survey

Updated February 2013

Overview

• What is the ACS Public Use Microdata Sample (PUMS) file?

• What geographic areas are available in the ACS PUMS?

• How does the Census Bureau protect confidentiality in the ACS PUMS?

• How do I access ACS PUMS data?

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What is the ACS PUMS file?

• A sample of population and housing unit records from the American Community Survey

• Allows users to create custom tables that are not available through pretabulated ACS products

• The 1-year ACS PUMS file represents 1 percent of the U.S. population

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Summary Data and Microdata What’s the Difference?

Summary data are predefined tables for specific geographic areas (states, counties, etc.)

In the ACS microdata, the basic unit is an individual housing unit or person

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Who Should Use the ACS PUMS?

• People who want to create tables that are not available through American FactFinder

• People who need data for small or unique population groups

• People interested in mapping population and housing characteristics

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Sample Questions That the ACS PUMS Could Answer

• What proportion of children ages 5 to 9 live in households that do not have telephone service?

• What is the veteran status of college students living in Maine?

• What proportion of low-income workers in Kentucky commute 90+ minutes to work?

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Overview





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Geographic Areas in the ACS PUMS

• Nation

• All states, D.C., Puerto Rico

• Public Use Microdata Areas (PUMAs)

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What are PUMAs?

• Predefined areas with 100,000+ residents

• Combinations of adjacent counties and census tracts within states

• PUMA boundaries match those used in Census 2000, with exception of Louisiana

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Identifying PUMAs

• PUMAs are identified by a five-digit number, unique within each state

• Geographic equivalency files show how other areas align with PUMA boundaries– Available at

http://www2.census.gov/census_2000/datasets/PUMS/FivePercent/

• Census 2000 PUMAs will continue to be used until after the 2010 Census

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Sample PUMA Map – County Groupings

•State PUMA maps are available on the Census Bureau website at http://www.census.gov/geo/www/maps/puma5pct.htm

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Sample PUMA Map – Subdivided County

PUMA boundary files available for download www.census.gov/geo/www/ cob/pu5_2000.html

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Overview





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Protecting Confidentiality in the ACS PUMS

• Title 13 requires the Census Bureau to keep all personal information strictly confidential:

– By stripping personal information from records

– Through “data swapping,” “top coding,” and “bottom coding”

– By including only a sample of ACS responses

– By limiting geographic areas on the PUMS

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Overview





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Accessing PUMS Files• Data can be downloaded through American

FactFinder and analyzed with statistical software

• Or accessed through the menu-driven DataFerrett system

• PUMS documentation available at http://www.census.gov/acs/www/data_ documentation/pums_documentation/

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ACS Content: Housing• Age of Householder• House Heating Fuel• Household Size• Kitchen Facilities• Occupancy and Vacancy• Owner Statistics• Plumbing Facilities• Race of Householder• Renter Statistics• Rooms and Bedrooms• Telephone Service• Tenure

• Units in Structure• Value of Home• Vehicles Available• Year Householder Moved Into

Unit• Year Structure Build

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ACS Content: Population• SOCIAL

– Ancestry– Citizenship & Year of Entry– Disability Status– Educational Attainment– Field of Degree– Health Insurance – Grandparents– Fertility– Language– Marital Status & History– Place of Birth– Migration– Relationship– School Enrollment– Veteran Status

• ECONOMIC– Employment & Work Status– Income & Earnings– Industry & Occupation– Class of Worker– Commuting– Poverty Status– SNAP Receipt

• DEMOGRAPHIC– Age & Sex– Race & Hispanic Origin

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Downloading ACS PUMS data

American FactFinder

http://factfinder2.census.gov

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Downloading ACS PUMS data

American FactFinder

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Other PUMS Resources American FactFinder

• Subjects in the PUMS

• Code Lists

• PUMS Top Coded and Bottom Coded Values

• PUMS Estimates for User Verification

• Accuracy of the PUMS

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Analyzing PUMS DataStatistical Software

• Use SERIALNO variable to merge housing and person records

• Apply person and housing weights to produce estimates of population and housing

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Analyzing PUMS DataCalculating Standard Errors

• Generalized variance formula – Easier, but less accurate results

• Replicate weights provided in the PUMS file – More complex, but more accurate results

• Both methods are described in Accuracy of the PUMS

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Analyzing PUMS Data DataFerrett

• Can be used to extract PUMS data using a menu-driven system

• Need to register to use DataFerrett

• Download DataFerrett and install it on your computer

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DataFerrett Website

http://dataferrett.census.gov/

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Availability of ACS PUMS Data

• Available each year beginning in 2000

• PUMS files for each dataset are released one to two months after each public release

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Additional ACS Resources

• ACS website (census.gov/acs)

• American FactFinder (factfinder2.census.gov)

• QuickFacts (quickfacts.census.gov)

• DataFerrett (dataferrett.census.gov)

• FAQs (https://ask.census.gov/faq.php?id=5000&rtopic=1805)

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Final Thoughts

• The U.S. Census Bureau measures the nation’s People, Places and Economy

• Census Bureau statistics are how America knows what America needs

• The Census Bureau is the leading source of quality, timely and relevant information about our nation’s people and economy

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Contact Information

Subscribe to “Email Updates”http://www.census.gov/acs

Visit the ACS/PRCS website:http://www.census.gov/acs

Contact by Telephone:1-800-923-8282

Submit a Question:https://ask.census.gov

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