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ACS Technical Issues

ACS Technical Issues. Leonard M. Gaines, Empire State Development. Outline. How the Census Bureau reviews the data before release Sub-county weighting Group Quarters controls Dealing with data breaks. Data Review Process. Major Questions. Is the geography correct?

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ACS Technical Issues

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  1. ACS Technical Issues Leonard M. Gaines, Empire State Development

  2. Outline • How the Census Bureau reviews the data before release • Sub-county weighting • Group Quarters controls • Dealing with data breaks

  3. Data Review Process

  4. Major Questions • Is the geography correct? • Are population estimates correct? • Are the weights correct? • Is the programming correct? • Are the edits correctly specified? • Are the data products correctly specified? • Do the data seem reasonable? • Are the metadata correct?

  5. Four Phases of Review • Metadata Review • Continuous • Edit Review • December • April-May • Data Review • 1-Year Data Review • June-July • Multi-Year Data Review • September-November • Data Product Review • 1-Year Data Product Review • February-March • July-August • Multi-Year Data Product Review • August-December 5

  6. Metadata Review • Includes, • Measures (ART) and Metarules (MYDR) • Data Dictionaries and Code Lists • Subject Definitions • User Notes • Comparison Documents • User Guides

  7. Edit Review • Verify edit specifications • Verify variable universes • Review tallies • Review matrix counts • Review consistency among variables • Review unweighted imputation rates • Examine edited frequency distributions by allocation flag values • Compare unweighted unallocated and allocated relative frequency distributions • Compare unweighted current-year and prior-year relative frequency distributions

  8. 1-Year Data Review • Compare current-year and prior-year summary distributions • Compare about 135 current-year and prior-year derived measures • Median Gross Rent • Percent of civilian veterans 18 and over who served in the Vietnam era • Compare ACS estimates with other Bureau estimates • Review weighted imputation rates • Compare weighted unallocated and allocated relative frequency distributions

  9. 1-Year Data Review Geography • Nation • States (including DC and Puerto Rico) • Counties with populations >= 65,000 (~ 800) • Places with populations >= 65,000 (~ 520)

  10. Multi-Year Data Review • POP and SEHSD review variable crosswalking and inflation adjustment on the unweighted multi-year microdata • ACS Coordination Staff review the multi-year core measures and report the results of their review to branches in POP and SEHSD • POP and SEHSD review the Coordination Staff materials and decide whether to clear or perform additional review • Selected POP and SEHSD branches review the disclosure avoidance performed on the multi-year microdata

  11. Multi-Year Data Review Geography • Nation • States • Counties • Census Tracts in DC, MD, VA, and WV

  12. 1-Year Data Product Review • Verify data product specifications • Verify any new or modified table shells • Verify the programming of any new or modified data products • Review new or revised iterated selected population profiles (SPPs)

  13. Multi-Year Data Product Review • Review the programming and formatting for any new or modified multi-year data product • Review the notes for any new or modified multi-year data product

  14. Weighting and Sampling Issues

  15. Sub-County Estimates – The Problem • Causes • Household population & housing units controlled at county / county group level • Group quarters controlled at state level • Total population controlled at county level • Dependent on response patterns within control area

  16. Sub-County Estimates – The Solution • Added Controls • Control to total housing unit and population estimates for sub-county local governments • Excludes areas such as • CDPs • School Districts • Census Tracts & Block Groups

  17. GQ Problem • ACS GQ sample is designed to produce state-level estimates of GQ population • Estimates of GQ population contribute to the total resident population for substate areas • As a consequence of sampling • Lack of representation of GQ sample for many small areas • Over-representation for other areas

  18. GQ – Possible Solution • Impute GQ person records to not-in-sample GQ facilities • Donors are the sampled GQ person records • Copy the donor person’s entire characteristics to imputed GQ • Implementation rules being tested through simulations

  19. GQ - Objectives • Operational Goals • Have evaluations completed this fall • Implement for 2006-2010, 2008-2010 and 2010 ACS estimates • Technical Objectives • If feasible – GQ representation, sample or imputed, by • Tract by major GQ type for 5-year data • County by major GQ type for 1- and 3-year data

  20. GQ - Status • Developed the basic imputation methodology • First part of evaluations completed • More work to do for 2010 estimates • Continue to improve methods for future ACS estimates

  21. Sampling Reallocation – The Problem • Currently use 7 strata for sampling • Estimated occupied housing units • Response rate • Very different CVs based on tract size • Table based on simulation of poverty rates

  22. Sampling Reallocation – The Solution • Start use 16 strata for sampling in January 2011 • Estimated occupied housing units • Response rate • Less variation in CVs based on tract size • CVs would decrease if Congress funds larger sample size

  23. Confusion & Data Breaks

  24. December’s Confusion • 2010 Census Releases • Demographic Analysis • Estimates of April 1, 2010 population • National only • Apportionment Counts • State and national only • Official April 1, 2010 population • Apportionment and resident populations • ACS Releases • 2005-2009 Data • Based on 2009 vintage population estimates for all years • 2009 Data (already available) • Based on 2009 vintage population estimates for 2009

  25. Geographic Changes • This year’s releases (2009 data) • Municipal Boundaries – January 1, 2009 • Statistical Boundaries – Census 2000 • Next year’s releases (2010 data) • Municipal Boundaries – January 1, 2010 • Statistical Boundaries • Census tracts & Block groups – 2010 Census • Urban areas, MeSAs/MiSAs, PUMAs – Census 2000 • Future releases (2011 data and beyond) • Municipal Boundaries – January 1 of last data year • Statistical Boundaries – Latest delineated boundary

  26. Control Changes

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