How Will the Changing U.S. Census Affect Decision-Making? David A. Swanson University of California Riverside David.swanson@ucr.edu Prepared for the Lewis Seminar May 15, 2008
ACKNOWLEDGMENTS In addition to original material, this presentation uses materials prepared by: (1) the U.S. Census Bureau; (2) Linda Gage, California Dept. of Finance; (3) David Drozd,, Nebraska State Data Center; and (4) David Swanson & George Hough (for the 2007 American Community Survey Conference)
OUTLINE THE DECENNIAL CENSUS AMERICAN COMMUNITY SURVEY (ACS) CENSUS LONG FORM ACS ACS DETAILS A NEW MENTALITY: CENSUS ACS DECISION-MAKING WITH THE ACS CONCLUSION
CENSUS The 2000 decennial census had two parts: 1) the short form, which counts the population; and 2) the long form, which obtains demographic, housing, social, and economic information from a 1-in1 in-6 sample of households.
CENSUS Information from the long form has been used for the administration of federal programs and the distribution of billions of federal dollars. Since this is done only once every 10 years, long-form information becomes out of date. Planners and other data users are reluctant to rely on it for decisions that are expensive and affect the quality of life of thousands of people.
LONG FORM ACS The American Community Survey is a way to provide the data that states, counties, and communities need every year instead of once in ten years. It will replace the decennial long form in future censuses and is a critical element in the Census Bureau's reengineered 2010 census.
LONG FORM ACS So, the 2010 decennial census will have only one part: The short form, which counts the population The long form will not be part of the 2010 census. Instead we will have the American Community Survey.
ACS DETAILS Full implementation of the American Community Survey will cover every state, county, city, census tract, and block group in the United States. The survey covers approximately three million households annually. Data are collected by mail and Census Bureau staff follow up with those who do not respond.
ACS DETAILS Full implementation of the American Community is complex, however, because it is a rolling sample and how often it rolls around depends on the size of the population in a given area.
ACS DETAILS
ACS DETAILS The American Community Survey will provide estimates of demographic, housing, social, and economic characteristics every year for all states, as well as for all cities, counties, metropolitan areas, and population groups of 65,000 people or more.
ACS DETAILS For smaller areas, it will take three to five years to accumulate sufficient sample to produce data for areas as small as census tracts. For example, areas of 20,000 to 65,000 can use data averaged over three years.
ACS DETAILS For rural areas and city neighborhoods or population groups of less than 20,000 people, it will take five years to accumulate a sample that is similar to that of the decennial census. These averages can be updated every year. Eventually, The Census Bureau plans to be able to measure changes over time for small areas and population groups.
Switching from a Census Mentality to the ACS Mentality
The Census and the ACS differ in fundamental ways 1. Timeframe Reference 2. Questions and Choices 3. Residency 4. Multiple Sets of Data for many Areas that are not consistent 5. Statistical Inference
1.Timeframe The Census was a point in time estimate (4-1-00); The ACS accumulates 12 months of data for a calendar year estimate, 36 months for 3 years and 60 months for 5 years
Comparison of "past 12 months" relative to the 2003 month of survey receipt 2002 2003 Relevant past 12 months Month of survey receipt J F M A M J J A S O N D J F M A M J J A S O N D X X X X X X X X X X X X Rec
Comparison of "past 12 months" relative to the 2003 month of survey receipt 2002 2003 Relevant past 12 months (also in 2003) Month of survey receipt J F M A M J J A S O N D J F M A M J J A S O N D X X X X X X X X X X X X Rec X X X X X X X X X X X X Rec X X X X X X X X X X X X Rec X X X X X X X X X X X X Rec X X X X X X X X X X X X Rec X X X X X X X X X X X X Rec X X X X X X X X X X X X Rec X X X X X X X X X X X X Rec X X X X X X X X X X X X Rec X X X X X X X X X X X X Rec X X X X X X X X X X X X Rec X X X X X X X X X X X X Rec Total Number of Months: 78 66 Percent of Total: 54 % 46 %
2. Some questions & answer choices differ EXAMPLES Change of residence Census: 5 years ago; ACS: 1 year ago Relationship to householder Census: son/daughter categories for natural-born, adopted, and step; ACS: only 1 category (son/daughter)
3. RESIDENCY CENSUS uses usual residence ACS uses two month rule
4. MULTIPLE SETS OF DATA Different estimates and how to use them Year over year comparisons now possible 3 or 5 year-estimates estimates for less-populated area
Over 1,000 school districts in California Over 9,000 individual schools Over 6,000,000 students in public schools Over 500,000 students in private schools We ll look at high school enrollments estimated in the ACS and as reported to the California Department of Education for a school district in Tulare County
TULARE COUNTY Multi-Year Enrollment Estimates
5. Statistical Inference ACS data include a lower and upper bound. Why? The ACS is a sample and subject to sampling error.
5. Statistical Inference Is the data representative of the entire population? The range between the lower and upper bound is called a confidence interval. ACS displays a 90% confidence interval. The bounds tell us that we are 90% confident that the figure for the entire population would be in this range if all households were surveyed.
TULARE HS 1-Year 1 Enrollment
TULARE 3-Year Enrollment Estimates
TULARE 5-Year Enrollment Estimates
Tulare High School Enrollment
TULARE ENROLLMENT Pick a Number, Any Number!
TULARE COUNTY, CA PPH 3.450 3.400 3.350 3.300 3.250 3.200 3.150 1 2 3 4 5 6 Year (2001-2006) ACSPPH ADPPH TULARE COUNTY, CA PPH 3.380 3.360 3.340 3.320 3.300 3.280 3.260 3.240 3.220 1 2 3 4 5 Year (1999-01 to 2003-05) ACSPPH3YR ADPPH3YR
DECISION-MAKING 1. Timeframe Reference 2. Questions and Choices (historical continuity) 3. Residency
DECISION-MAKING 4. Multiple Sets of Data for many Areas that are not consistent 5. Statistical Inference AND 6. Consistency with 2010 Short Form an unanswered question
CONCLUSION THE AMERICAN COMMUNITY SURVEY WILL PLACE A MUCH HIGHER INTERPRETATION BURDEN ON USERS THAN DID THE TRADITIONAL SHORT-FORM / LONG-FORM DECENNIAL CENSUS. Dig out your statistics textbooks and pray for convergence of multi-year estimates!
ACS INFORMATION ACS CONTACTS American Community Survey Web site site site (www.census.gov/acs/www) Call ACS Staff at: at: 1-888-346-9682 E-mail ACS staff at: cmo.acs@census.gov Subscribe to the ACS Alert