A Guidebook for Using American Community Survey Data for Transportation Planning (2007) / Chapter Skim
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Appendix I - Comparison of ACS and Decennial Census Transportation Planning Estimates
Appendix I - Comparison of ACS and Decennial Census Transportation Planning Estimates
Pages 253-262
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From page 253... ...
The standard errors of the ACS estimates were calculated by the Census Bureau and provided in the datasets used for this analysis. Since the CTPP standard errors were unavailable, we computed them using the methods described in the SF3 documentation, Section 8, "Accuracy of the Data." For the purpose of statistical significance testing, the difference in estimates is defined as the ACS count minus the CTPP count (note that for several of the tables provided, the ACS and CTPP estimates are means and medians)
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254 A Guidebook for Using American Community Survey Data for Transportation Planning County Census Tract-Level Data Census TAZ-Level Data Pima County, Arizona San Francisco County, California Broward County, Florida Lake County, Illinois Hampden County, Massachusetts Douglas County, Nebraska Franklin County, Ohio Multnomah County, Oregon Bronx County, New York Source: Federal Highway Administration, 2004. Table I.1.
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Residence-based evaluation dataset tables.
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From page 256... ...
Workplace-based evaluation dataset tables. 1 2 3 4 5 6 7 8 9 10 11 Table Universe Content Total Workers Vehicles Available per Household by Mode to work Means of Transportation Household Income by Means of Transportation Mean Travel Time by mode to work by Time Leaving Home Median Travel Time by mode to work and Time Leaving Home Aggregate Number of Vehicles by Time Leaving Home for Work Average Number of Workers per Vehicle by Time Leaving Home Aggregate Number of Carpools by Time Leaving Home for Work Number of Workers per Carpool by Time Leaving Home for Work Workers in Households Aggregate travel time by mode to work and Time Leaving Home Source: Federal Highway Administration, 2004.
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Estimate of Workers Driving Alone-95 Percent Confidence Intervals (San Francisco County, California)
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Estimate of Workers Driving Alone-95 Percent Confidence Intervals (Broward County, Florida)
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Estimate of Workers Driving Alone-95 Percent Confidence Intervals (Douglas County, Nebraska)
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Estimate of Workers Driving Alone-95 Percent Confidence Intervals (Franklin County, Ohio)
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From page 261... ...
We evaluated the following variables at the county and tract levels: mode to work, vehicles available by mode to work, mean travel time by mode to work, worker earnings, and mean earnings by mode to work. The general conclusions from the workplace-based evaluation are: • The differences in the estimates between ACS and Census tend to be larger as the geographic level becomes smaller due to the larger variances in the ACS estimates; and • Overall, the ACS estimates do not seem to be biased; the distributions of the differences between ACS and Census estimates are not skewed in a certain direction.
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From page 262... ...
Comparison of ACS and Census 2000 worker flow data for tracts in San Francisco County. Worker Flow-Based Evaluation The worker flow evaluation datasets did not allow for a meaningful comparison of the differences between ACS and CTPP, because: • The test site data were only for isolated counties, so only the worker flows with both trip ends in the counties were available; and • The disclosure limitations placed on the ACS test data were probably different than will be employed for actual future releases of the data, so conclusions about the test data are not likely to be valid.
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