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CTPP Data Products

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4/01/2009 (revised 4/13, 4/28, 4/29, 5/14)

This Excel workbook contains the specifications for the Census Transportation Planning Products (CTPP) special tabulation using 3-year data.

DATA: The tabulation should be processed using the ACS 2006-2008 dataset.

A brief description of the tabs in this workbook:

"Geog" defines all geographies to be used with which tables.

"Universes" defines all universes to be used with the tables.

"Variables" defines all variables that are referenced in the tables lists.

"Tabs-Part1"defines residence geography tables, variables, universes, number of cells, and table numbering (Columns E-I). Table numbers can be prefixed with "T".

"Tabs-Part2" defines workplace geography tables, variables, universes, number of cells, and table numbering (Columns E-I). Except where noted, the universes include workers who worked at home (for whom workplace geocode is the same as the residence geocode). Table numbers can be prefixed with "T".

"Tabs-Part3" defines residence to workplace flow geography tables, variables, universes, number of cells, and table numbering (Columns E-I). Except where noted, the universes include workers who worked at home (who reside and work in the same geocode). Table numbers can be prefixed with "T".

FILE FORMAT requirements:

Standard Errors: The tabulation should include the standard errors (SEs) in addition to the 90% margins of error (MOEs). In other words, for each cell, please include the estimate, the 90% MOE, and the standard error. The standard error should be provided to 2 decimal places more than the relevant estimate. Please include this in the cost estimate.

Guidance: AASHTO requests that the Census Bureau provide guidance and special instructions, if any, on the recalculation of margins of error for aggregations of geographic units, variable categories, or different levels of statistical significance.

Output file number format: Please remove the "+/-" from the MOEs and also make all numbers (estimates, MOEs, and SE s) in numeric form in the output file.

Specific file structure, sequence of numbers, and format to be determined. File structure must accommodate numeric format and no "+/-". We understand that .CSV and SAS dataset file formats can be provided automatically. Please add a time and cost estimate for the Summary File ASCII files option (3 separate tables for each of estimates, SEs, and MOEs).

For the DRB- Changes since the 2008 CTPP table submission:

Variables Crosstabulated with Means of Transportation:

The number of variables crossed with Means of Transportation have been reduced to 5 across all three geographic levels. The five variables are: travel time, household income, vehicle availability, age, and time leaving home (residence geography)/ time arriving at work (workplace geography). Note that Time Arriving at Work at workplace geography is a simple transformation of Time Leaving Home at residence geography and therefore is not a distinct variable.

In contrast, the 2008 submission had 18 crosstab variables for residence geography, 17 crosstab variables for workplace geography, and 6 crosstab variables for home-to-work flows.

Tables:

All three-way categorical tables with Means of Transportation have been eliminated.

All crosstab tables involving Means of Transportation are now defined with more collapses with more aggregated categories. There are now have 4 versions in the residence and workplace tables and 2 versions in the flow tables.

Resulting tables consist of the same 1 univariate and 11 unique means of transportation crosstab tables across only 5 crosstab variables, for all three geographic types: Residence, Workplace, and Home-to-Work Flows.

See the table below for a summary of tables involving Means of Transportation

4/13/0

Means of Transportation Tables and Crosstab Variables in the CTPP
  Residence Geography Workplace Geography  Home-to-Work Flows 
New 2009 Request      
Number of variables crossed with means of transportation 5 5 5
Number of Tables with Means of Transportation:      
Univariate  1 1 1
Unique Crosstabs 11 11 11
2008 Request      
Number of variables crossed with means of transportation 18 17 6
Number of Tables with Means of Transportation:      
Univariate  1 1 1
Unique Crosstabs 34 31 7

4/13/09 Geography Note: Since the 4/01/09 submission, three summary levels were removed from the request. In Part 1 Residence Geography, POWPUMA was removed, in Part 2 Workplace Geography, PUMA5, and in Part 3 Home-to-Work Flows, POWPUMA-to-POWPUMA flows. This was done to address the DRB's concerns about publishing data for the slivers created between the PUMA5's and the POWPUMA's.

4/28/09 Change of Flow Table. The transportation community requested changing univariate table number 32106, Line 8 of the Part 3 Home to Work Flows from Means(11) to Means(18). The DRB approved the request on 4/27/09.

4/29/09 Minor Corrections to Variables and Tables. All of the following changes correct inconsistencies. Changes (ii) and (iii) result in a slight reduction in the number of cells used in those tables. (i) Variable "Age (6)" renamed to "Age of worker (6)". Name change affects Part 3 Tables 32201, 32201C. (ii) Tables using Age (9) changed to use Age of worker (8) (which excludes "Under 16 years" category) where inconsistent with worker universe. Change made to Part 1 Tables 12200, 12201, 12201C, 12201C2, 12201C3, and to Part 2 Tables 22200, 22201, 22201C, 22201C2, 22201C3.  (iii) Variable "Age of worker (10)" created to be the same as Age (11) but without the "Under 16 years" category. Tables using Age (11) changed to use Age of worker (10) where inconsistent with worker universe. Change made to Part 2 Table 22101. "Variables" tab updated and reordered accordingly.

5/14/09 Disability. All 4 disability tables are removed, due to the substantial changes in the disability questions between 2007 and 2008. These tables are: 11102 Any Disability (4); 11200 Age (11) by Disability (4); 11204 Employment status (7) by Disability (4); and 22110 Any disability (4) at workplace geography.

Updated: 05/05/2011
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