Presentation on theme: "Wrapping up the CTPP Wrapping up the CTPP What you should know What you should know Ed J. Christopher FHWA Resource Center near Chicago 19900 Governors."— Presentation transcript:
Wrapping up the CTPP Wrapping up the CTPP What you should know What you should know Ed J. Christopher FHWA Resource Center near Chicago 19900 Governors Drive Olympia Fields, IL 60461 708-283-3534 email@example.com April 26, 2005
Today Run Through CTPP Cover Some CTPP/Census Data Issues
What is the CTPP? The Census Transportation Planning Package is a set of special tabulations from the long form of the decennial census designed by transportation planners for transportation planners It summarizes the data At Residence At Workplace Flows between Home and Work
CTPP Main Products Tabulations at Residence Tabulations at Workplace Flows between Home and Work Part 1Part 2Part 3 Part 1Part 2 Part 3
The CAT CTPP Access Tool How is it packaged? ASCII Too
Part 1 -- Residence Data (Done) BTS has Final ASCII version on TranStats Final CAT Files distributed to MPOs / states Part 2Work Place Data (Done) Final ASCII on BTS TranStats Final CAT @ BTS Bookstore Final CAT @ BTS Bookstore Part 3 Flow Data Final ASCII (Done) Coming Soon!!!!! When was it released?
Where do I get the FREE CTPP ASCII Files? http://www.transtats.bts.gov/
Where do I get the FREE CTPP with Software? https://www.bts.gov/pdc/
Mode to Work Circa 1990 For 2000 (ROUNDED) Total352350 (not 355!) Drive Alone212210 Carpool4645 Transit5960 Walk3335 Bike24 Example of Rounding True Total 354
Using the CTPP, 10 + 10 + 10 + 10 = ? Pop Quiz! a) 30c) 35e) 40 b) 45d) 50f) Any of the Above Here's a real life example using the CTPP Part 2 data. Let's say my boss asks as simple question: "How many transit commuters are at work in the Bay Area?" Using the Part 2 data, I am able to provide my boss 15 different answers! Chuck Purvis, MTC
1.Obtain your "regional control totals" from the most geographically aggregate summary levels 2.Avoid aggregating (summing together) your geographies 3.Avoid aggregating categories 4.Sum as few categories as possible 5.Adjust (de-round, un-round) as you see fit. SF3 or PUMS can provide control totals to adjust the CTPP Part 1 data. 6.Develop a sense of humor. Rounding Tips So is it "close enough for government work?"
http://www.trbcensus.com/articles/ctppworkers.pdf Workers at Work Counts vs. Other Employment Sources Total jobs are HIGHER than Census 2000 worker counts while CTPP Part 3 is Lower yet! (Rounding) CTPP uses NAICS, others may use SIC Multi-site businesses and job types not reported consistently Census 2000 employment estimates vs CPS Extended Allocation for CTPP small areas
Top Coding of Travel Time The top coding of travel time changed between 1990 and 2000. In 1990, the data field for travel time was limited to 2 digits thereby restricting travel time to a maximum of 99 minutes. In 2000, the field was 3 digits with a top coding of 200 minutes.
When I get my CTPP data what should I do? Examine the data for your area as soon as possible Check its reasonableness Does it make sense? Are people working where they should be? Do the tables add up? Report all data issues to Nanda Srinivasan, FHWA, (Phone 202-366-5021, email firstname.lastname@example.org)
Stay Connected Are You on the CTPP-News Listserve? Have You Seen our Newsletter (the Status Report)? http://www.dot.gov/ctpphttp://www.TRBcensus.com202-366-5000
When Mining Your Census Data Keep us in Mind Let Us Know What You Have Done We Are Always Interested Want to… Want to… Show Off Your Work? Show Off Your Work? Gain National Exposure? Gain National Exposure? Meet Other Data Users? Meet Other Data Users? Tour Washington DC? Tour Washington DC? Sound Exciting? TRB Urban Data and Information Systems Committee Ed Christopher-Chair (708-283-3534)
Now lets head off to the races with our latest CTPPs