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Census Data for GIS and Planning Professionals GIS in Action April 15, 2014

Census Data for GIS and Planning Professionals GIS in Action April 15, 2014. Charles Rynerson Census State Data Center Coordinator Population Research Center College of Urban and Public Affairs. Topics. Accessing Census Data Tabular Data Data for GIS projects Understanding Census Data

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Census Data for GIS and Planning Professionals GIS in Action April 15, 2014

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  1. Census Data for GIS and Planning Professionals GIS in Action April 15, 2014 Charles Rynerson Census State Data Center CoordinatorPopulation Research Center College of Urban and Public Affairs

  2. Topics • Accessing Census Data • Tabular Data • Data for GIS projects • Understanding Census Data • Cautionary Tales

  3. Block Group Data!

  4. The “Summary File”

  5. 100% Count and Sample Data • Sampling Error • Non-Sampling Error • ACS Population Controls

  6. 259 ÷1893 = 0.137 13.7% of households sampled

  7. Example 3 – The Published Tables Are But One Representation of Reality • The following example shows the large sampling variability in the block group data using % rental households of all single family households. • The universe of households was recreated from the 100% data from the 1990. • 20 random samples were drawn on a 1 in 6 basis. • Choropleth maps were draw for each sample? • Which map is the right one, the best representation of reality? NACIS 2008

  8. Here are 20 “might have been” samples for 1990 SF3 sample data • The following sequence shows 20 possible sets of data that might have been obtained in the sampling process. • Note the considerable local variation but also the persistence of some of the high values • The lesson: Be cautious about interpreting small area sample census data. Which of these 20 representations of reality is closest to the truth? NACIS 2008

  9. What is Non-Sampling Error? Definition Any error affecting a survey or census estimate apart from sampling error Occurs in complete censuses as well as in sample surveys

  10. Types of Non-Sampling Error • Non-Response Error • Response Error • Processing Error • Coverage Error

  11. 1241 ÷1888 = 0.657 Income imputed for 34.3% of households

  12. 271 ÷5180 = 0.052 5.2% of housing units sampled

  13. 3931 ÷4196 = 0.937 Income imputed for 6.3% of households

  14. Population Controls • Independent information used to increase the precision of the ACS estimates • Reduces sampling and non-sampling errors in the ACS estimates • Time series of population estimates are revised annually but the ACS estimates for previous years are not. 25

  15. Census Geography Hierarchy (with 2010 Statistical Area Criteria) Revised 10-29-11 Central axis describes a nesting relationship • Cities and towns -- incorporated • Census Designated Places (CDPs) • 1,200 to 8,000 population (optimum 4,000) • 480 to 3,200 housing units Blocks are not defined by population and are the smallest geographic level at which data are ever released (Decennial Census, not the ACS) • 600 to 3,000 population • 240 to 1,200 housing units

  16. 2010 Census: Race and Ethnicity • Use decennial censuses for race and ethnic population counts, not ACS • Changes between 1990 and 2000 • Consistent reporting between 2000 and 2010 • Two questions: 1. Hispanic/Latino? 2. Race? One or more boxes

  17. 2010 Census: Race and Ethnicity 2000 2010 change

  18. Census Data for GIS and Planning Professionals GIS in Action April 15, 2014 Charles Rynerson Census State Data Center CoordinatorPopulation Research Center College of Urban and Public Affairs

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