[CTPP] Re: CTPP 2000 TAZ Update Program

Bob: I will attempt to answer your questions, and distribute my response to you, to a number of individuals, and to the CTPP news group on the off chance that others may have similar concerns. Here goes. 1) The effect of participation in the TAZ update program on the CTPP data that will be available is simple. If you want any TAZ level data out of the 2000 CTPP, you must participate in the TAZ update program. If you want CTPP data only for standard census geography, either tracts or block groups (you choose which one), then you don't need to participate in the TAZ update program. You asked about CTPP data available on the Internet. Right now, we don't know if there will be any CTPP data available over the internet. We are currently discussing the design, content, products, etc. of the 2000 CTPP with DOT. (For general information and updates you might want to join the CTPP news group, ctpp-news(a)chrispy.net. Instructions for subscribing may be found at the URL http://www.mcs.com/~berwyned/census. Note that there is lots of other interesting stuff presented there, courtesy of Ed Christopher of the Chicago Area Transportation Study and others.) Anyway, what we do know is that there won't be CTPP data, nor any commuter flow data, nor any specific workplace data, available through the Census Bureau's decennial web access, once called the Data Access and Distribution System (DADS) but now known as the American FactFinder. Flow data, or any data tabulated by workplace instead of by residence, has been determined to be out of scope for American FactFinder. In our discussions with DOT we have outlined a 2000 CTPP that would consist of a Statewide Element and an Urban Element. Each element would contain a set of residence-based tables, a set of workplace-based tables, and a set of origin by destination tables. These sets of tables will be standard for all areas. Our assumption is that for a whole state in the statewide element or for an MPO area in the urban element, the volume of data would be too great to ask people to download it over the net. So we think we will distribute the 2000 CTPP on CD (or some other high capacity medium) again. This time, however, we will provide the access software ourselves and deliver just one integrated product, data and software at the same time. However, DOT has indicated (and I agree) that it would be nice to be able to have some kind of data on demand system available for CTPP customers over the net. But this is still just an idea at this point. We don't know if it's feasible, how expensive it would be to develop, how it would work, etc. We'll try to keep people posted on the status; right now we've agreed to look into what it would entail, but have not promised to provide such functionality as part of the CTPP. 2) I'm not the best person to ask what standard geography will be available from American FactFinder. I'm not sure the decision has been made yet. I would guess that you'll be able to retrieve anything that has been released on a summary tape file. This would imply that you could get individual data items for tracts and block groups of residence. It sounds like there may be some multi-variable crosses that will be available for tracts, but not for BGs (too much detail for the finer geography). In general, there could be some differences like this in what data are available based on the size of an area, but I think this would be the only criterion. As I noted above, there won't be CTPP data available, nor any flow data, nor data by place of work from American FactFinder. There will probably be recodes like worked in same county, diff. county, diff state, etc. I don't know what the current plans are for data on demand over the net through American FactFinder. They might accept specs for custom tallies from PUMS, but this would be for large geographic units. I don't know if there will be any facility for doing custom tables from the full sample (i.e., not PUMS). Even if you wanted TAZ of residence only (no flows or at-work data) I don't know if TAZ is a piece of geography that will be supported. It could be, because we intend to provide it on the internal files we use for tabulations, but that doesn't mean they'll make it available over the net on demand. I see on the Census web site that questions about 2000 are supposed to be directed to 2000usa(a)census.gov. You could try this and see what you get. I'd be interested in seeing their reply. 3) If an MPO does not participate in TAZ-UP, we will ask them to choose tracts or block groups as their smallest geographic unit in the 2000 CTPP. 4) I'm not sure I understand this question. In the Urban Element, the MPOs choices are taz (if you've participated in TAZ-UP), tract, or BG. You'll have to pick one. 5) Our assumption so far has been that MPOs will have the choice described above for urban element geography. This would only cover the counties situated in the MPO areas. However, all counties would be included in the statewide element and there would be summary levels for counties and places of say 2,500 or more residents in the statewide element (as in the 1990 CTPP). Massachusetts (as well as some other New England states) may be an exception in that the whole state may be covered by MPOs (RPAs in Mass) and therefore the whole state may be included in the urban element at the taz, or tract, or block group level. 6) The Census Bureau's policy is that the most detailed level of geography we will show for sample (long form) data is the block group. That is why MPOs can choose between BGs and tracts for their CTPP. In the past we have treated TAZs as BG-like units and provided sample data for TAZs in the CTPP as well. There seems to be more concern for 2000 within the Census Bureau that BGs, and by implication BG-like units, may be too small to support some of the large (in terms of number of cells) tables created for them in the past. 7) Again, I'm not sure what you are asking. In standard census data products like STF3A on CD-ROM the entire hierarchy is available, from Block Group to whole state totals. In printed reports, totals for places above some size cutoff are usually available. There have also been printed data available in the past for census tracts by residence, but I don't know if that will happen for 2000. In the CTPP, you pick one of the three as your most detailed level. 8) Even if an MPO, or region, or county used TAZs in the 1990 CTPP and those TAZs were inserted into TIGER, and they think they don't want to make any changes to the boundaries, they still have to participate in the TAZ-UP program if they want TAZ data from the CTPP in 2000. It is entirely possible that some of the lines used as TAZ boundaries in 1990 will not be available for use in 2000, so boundaries will need to be adjusted. But in addition, for 2000 there will be many more lines that will be eligible to be used for TAZ boundaries, since MPOs won't be constrained to build them up from census tabulation blocks. This means it should be easier for the MPO to approximate the true TAZ boundaries than it has been in the past. Sorry this has run on so long. Please call me at (301) 457-2454 if I've missed the boat and failed to clearly answer your questions. --Phil ______________________________ Reply Separator _________________________________ Subject: CTPP 2000 TAZ Update Program Author: "Frey-DPW Bob" <Bob.Frey(a)state.ma.us> at SMTP-GATEWAY Date: 11/30/1998 3:36 PM Hello Phil: Bob Frey from the Massachusetts Highway Department here. We have had several discussions concerning CTPP in past years, and I'm hoping you can help again. Todd Blair suggested I contact you to get some further clarification regarding the TAZ Update program: 1) Will TAZ update participation status have any effect on what CTPP data will be available on the internet, or will a standard set of reports be available for all areas? 2) And what standard census geography will be available on the internet, and does this differ depending on the area? 3) If an MPO choses not to participate in the program, what is the default delineation for 2000 CTPP data (census tracts, block groups, or 1990 TAZ boundaries)? 4) In this situation, would block groups be available to every area anyway? 5) If not, will the CTPP data be available only to the level of tracts for rural areas, and down to block groups for urbanized areas? 6) Exactly what determines the lowest level of census geography available for the data in a given region? 7) Program participation aside, how can I determine what will be available throughout Massachusetts in terms of tracts/block groups? 8) If a region/county wants to keep their 1990 TAZs without changes, do they still need to participate in the TAZ Update Program to confirm this? If you could get back to me soon by phone or e-mail I would greatly appreciate it. Thanks, Bob Frey MassHighway Planning (617)973-7449 bob.frey(a)state.ma.us