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Understanding Census Geography

Understanding Census Geography. Lisa Neidert NPC Workshop : Analyzing Poverty and Socioeconomic Trends Using the American Community Survey July 12 – July 15, 2010. Census Geography. Geographic Areas: with 1-year and 3-year data. Geographic Areas: with 1-year and 3-year data.

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Understanding Census Geography

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  1. Understanding Census Geography Lisa Neidert NPC Workshop: Analyzing Poverty and Socioeconomic Trends Using the American Community Survey July 12 – July 15, 2010

  2. Census Geography

  3. Geographic Areas:with 1-year and 3-year data

  4. Geographic Areas:with 1-year and 3-year data

  5. What’s available in the ACS for single year data: via maps • Maps showing counties and places for each state (or the nation) • http://www.census.gov/acs/www/Products/users_guide/acs_2008_reference_maps.htm

  6. Counties with single year data: ACS 2008

  7. Almost all counties:DE, MA

  8. Few counties, no places:VT and WY

  9. State with American Indian Places: AK, AL, LA, NC, OK

  10. Counties with 3-year data:ACS 2006-2008

  11. States where all counties are over 20,000 • Connecticut • Delaware • District of Columbia • New Hampshire • New Jersey • Rhode Island

  12. What geographies are available in the 2006-2006 ACS http://www.census.gov/acs/www/acs-php/2006_2008_beginner_users_guide.php

  13. Geographical Areas (Texas):Covered in 2006-2008 • ACS 2006=2008 Geographical Areas

  14. What’s available in the ACS: via Look-up tables • Geographic entities available for 1-year data (2008) • Geographic entities available for 3-year data (2006-2008)

  15. Not ready for prime-time:census tracts and zip codes • Need 5-year estimates file • 2005 – 2009 • Available 2010 for Census Tracts; • 2011 for Zip Codes • Annual updates thereafter • 2006 – 2010 • 2007 – 2011, etc. • Possible delay for 5-year data • – only an unsubstantiated rumor

  16. ExampleCensus Tracts for community districts

  17. Zip codes • Not census geography • However, big demand for zip code data • Census Bureau builds ZCTAs via census blocks • ZCTA FAQs • http://www.census.gov/geo/ZCTA/zctafaq.html • Fun resource • http://en.wikipedia.org/wiki/Zip_code

  18. What to do with a 2011 release of zip code data? • See Exercise 4: • http://www.psc.isr.umich.edu/dis/workshop/npc2010/Exercise4_DealingWithDelays.pdf • This exercise shows how to build zip code characteristics from census tract characteristics

  19. What are PUMAs? • Public Use Microdata areas • Combination of population geographies that sum to at least 100,000 population. • In rural areas, several counties will form a PUMA. In an urban area, a county will be subdivided into multiple PUMAs. • PUMAs do not cross state boundaries

  20. PUMAs. . . . • PUMAs do not have good comparability over time (1990, 2000). • PUMA geographies for the ACS are the same as the 2000 boundaries • PUMAs are reasonable substitutes for counties • Smallest geography available in the microdata.

  21. PUMAs • Can be valuable for bypassing geographic restrictions when one wants national information at the county level • Create pseudo counties based on a cross-walk between PUMAs and counties

  22. Statistics based on 1-year ACS data Unit is county

  23. Statistics based on 3-year ACS dataUnit is county

  24. Statistics based on 1-year ACS dataUnit is PUMA

  25. Illinois example:PUMA to county example

  26. PUMA to County Widget • Based on PDQ-Explore output • http://www.psc.isr.umich.edu/dis/data/resource/detail/1527 • Based on American FactFinder output • http://www.psc.isr.umich.edu/dis/data/resource/detail/1528 • Try one this week

  27. Class Exercises Today • http://mblog.lib.umich.edu/NPC2010/archives/class_exercises/index.html • Poverty Hot-spots (ACS 2008) • Census tract data (Census 2000) • Bulk downloads, zip code (Census 2000) • Dealing with Delays: Creating zip code characteristics from census tract data

  28. PUMAs via Maps • Reasonable tool for rural parts of a state • Somewhat unwieldy for urban areas • Multiple maps per state http://usa.ipums.org/usa/volii/2000pumas.shtml

  29. PUMAs via text • Describes PUMA composition • By: • County • County subdivision • Place • Census tract • http://usa.ipums.org/usa/volii/2000pumas.shtml • http://www.psc.isr.umich.edu/dis/data/ref/PUMA/SUPERPUMA-2000-5pct.html

  30. Metropolitan areas • Defined by Office Management Budget (OMB) • http://www.census.gov/population/www/estimates/metrodef.html • Historical Definitions • http://www.census.gov/population/www/estimates/pastmetro.html • Researcher is free to follow own definitions • Census Bureau follows OMB definitions

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