Introduction to the Public Use Microdata Sample PUMS

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? 2

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 3

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 4

Who Should Use the ACS PUMS? • People who want to create tables that are not available through American Fact. Finder • People who need data for small or unique population groups • People interested in mapping population and housing characteristics 5

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? 6

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? 7

Geographic Areas in the ACS PUMS • Nation • All states, D. C. , Puerto Rico • Public Use Microdata Areas (PUMAs) 8

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 9

Identifying PUMAs • PUMAs are identified by a five-digit number, unique within each state • Geographic equivalency files show other areas align with PUMA boundaries – Available at http: //www 2. census. gov/census_2000/dataset s/PUMS/Five. Percent/ • Census 2000 PUMAs will continue to be used until after the 2010 Census 10

Sample PUMA Map – County Groupings • State PUMA maps are available on the Census Bureau website at http: //www. census. gov/geo/www/m aps/puma 5 pct. htm 11

Sample PUMA Map – Subdivided County PUMA boundary files available for download www. census. gov/geo/www/c ob/pu 5_2000. html 12

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? 13

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 14

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? 15

Accessing PUMS Files • Data can be downloaded through American Fact. Finder and analyzed with statistical software • Or accessed through the menu-driven Data. Ferrett system • PUMS documentation available at http: //www. census. gov/acs/www/data_ documentation/pums_documentation/ 16

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 17

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 18

Downloading ACS PUMS data American Fact. Finder http: //factfinder 2. census. gov 19

Downloading ACS PUMS data American Fact. Finder 20

Other PUMS Resources American Fact. Finder • Subjects in the PUMS • Code Lists • PUMS Top Coded and Bottom Coded Values • PUMS Estimates for User Verification • Accuracy of the PUMS 21

Analyzing PUMS Data Statistical Software • Use SERIALNO variable to merge housing and person records • Apply person and housing weights to produce estimates of population and housing 22

Analyzing PUMS Data Calculating 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 23

Analyzing PUMS Data. Ferrett • Can be used to extract PUMS data using a menu-driven system • Need to register to use Data. Ferrett • Download Data. Ferrett and install it on your computer 24

Data. Ferrett Website http: //dataferrett. census. gov/ 25

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 26

Additional ACS Resources • • • ACS website (census. gov/acs) American Fact. Finder (factfinder 2. census. gov) Quick. Facts (quickfacts. census. gov) Data. Ferrett (dataferrett. census. gov) FAQs (https: //ask. census. gov/faq. php? id=5000&rtopic=1805) 27

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 28

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 29