1. Integrating ACS with the World’s Census Data: ACS Microdata and the IPUMS Presented at the Pre-ALAP ACS/IPUMS Workshop November 16, 2010 Trent Alexander American Community Survey Office U.S. Census Bureau

2. Outline American Community Survey (ACS) Overview and ACS PUMS Integrated Public Use Microdata Series (IPUMS) How the ACS PUMS fits in ACS and the world’s population data heritage Does the ACS model work? 2

3. Microdata versus Summary Data Microdata “Raw” data containing each person’s responses Enables custom tables and analyses Limitations: geographic identifiers, fewer cases, less reliability Summary Data Premade or published tables Enables examination of small geographic areas Limitations: limited content 3

4. Summary Data 4 Source: 2009 ACS 1-year Estimates. Table B15003. EDUCATIONAL ATTAINMENT FOR THE POPULATION 25 YEARS AND OVER - Universe: POPULATION 25 YEARS AND OVER.

5. Microdata 5 Source: 2000 Census PUMS.

6. Microdata 6 Source: 2000 Census PUMS.

7. Overview of the ACS An on-going nation-wide survey providing reliable annual data Conducted in every town and county Includes housing units and group quarters 7

8. Samples approximately 2.9 million addresses per year 21 questions about housing unit 48 questions about each person 8 Basic ACS statistics

9. Similar to decennial “long form” data About 1,000 tables for each geographic area –for 370,000 areas in newest data Annual PUMS samples for ~1% of population 9 ACS Data Products

10. Person records in ACS PUMS (millions) Person records in ACS complete data (millions) Population (millions) 20011.21.3285 20021.21.3287 20031.21.3290 20041.21.3293 20053.04.5296 20063.04.5298 20073.04.5301 20083.04.5304 20093.04.5307 10 Source: B00001. UNWEIGHTED SAMPLE COUNT OF THE POPULATION - Universe: TOTAL POPULATION. B01001. SEX BY AGE - Universe: TOTAL POPULATION

11. How does this compare to a decennial census PUMS? 11

12. 12 Census 2000 PUMS ACS PUMS Geographic DetailAreas of 100,000+ % Sample per decade6%10% Data collection period~4 months1+ years

13. Less obvious benefits of ACS Permanent staff –high-quality data collection –consistent standards for processing, editing, etc. Changes are infrequent and well-documented Ongoing support for products Ability to fix errors and make improvements 13

14. What do PUMS users think? 14

15. IPUMS – Public Data Samples Integrated - consistent codes, labels, and documentation Public Use - anonymized, downloadable Microdata - individual-level Series - pooled data over time and place 15

16. http://www.ipums.org/ 16

17. IPUMS-USA Samples from United States and Puerto Rico U.S. decennial census and ACS data,1850-2009 Various specialty samples (longitudinal, oversamples) ACS PUMS availability All ACS samples from 2000-2009 17

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20. ACS in IPUMS-USA: Extremely popular Most requested IPUMS-USA sample this year: 2008 ACS PUMS About half of all extracts include ACS data 2 nd most common search term leading to website: “ipums acs” (most common is “ipums”) 20

21. IPUMS-International World’s largest collection of public census data Has 159 census samples from 55 countries Incorporating latest censuses and new countries ACS PUMS availability 2005 ACS PUMS only 21

22. ACS in IPUMS-International: Not as popular 2005 ACS not among the most requested samples U.S. Census 2000 requested much more often than ACS Will this change when 2010 round of censuses is posted? Should IPUMS-Intl include 2010 ACS 1-year data or 2006-2010 pooled 5-year data? 22

23. Contact Information Trent Alexander j.trent.alexander@census.gov ACS User Support acso.users.support@census.gov IPUMS User Support ipums@pop.umn.edu 23