From MackCE@dshs.wa.gov Mon Jul 9 14:59:25 2001 Received: from mxu4.u.washington.edu (mxu4.u.washington.edu [140.142.33.8]) by lists.u.washington.edu (8.11.2+UW01.01/8.11.2+UW01.04) with ESMTP id f69LxN055870 for ; Mon, 9 Jul 2001 14:59:23 -0700 Received: from dshsmsg2 (dshsmsg2.dshs.wa.gov [147.56.131.10]) by mxu4.u.washington.edu (8.11.2+UW01.01/8.11.2+UW01.04) with SMTP id f69LxNs28949 for ; Mon, 9 Jul 2001 14:59:23 -0700 Received: from 147.56.131.30 by dshsmsg2 with ESMTP (DSHS MMS SMTP Relay (MMS v4.7)); Mon, 09 Jul 2001 14:59:19 -0700 X-Server-Uuid: 1a548dfa-be79-11d4-99cf-009027d0d054 Received: by dshsmsg4.dshs.wa.gov with Internet Mail Service ( 5.5.2653.19) id ; Mon, 9 Jul 2001 14:59:19 -0700 Message-ID: From: "Mack, Curtis" To: "'waphgis@u.washington.edu'" Subject: RE: Zip Codes, ZCTA and areal interpolation. Date: Mon, 9 Jul 2001 14:59:20 -0700 MIME-Version: 1.0 X-Mailer: Internet Mail Service (5.5.2653.19) X-WSS-ID: 1754F6BD1136202-01-01 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: 7bit I couldn't agree more! Curtis Mack MackCE@dshs.wa.gov Geographic Information Specialist (360) 902-0747 Washington State 47.0356 N by 122.8946 W Dep. of Social & Health Services MS-45204 OB2 14th & Jefferson Research & Data Analysis Olympia, WA 98504-5204 > -----Original Message----- > From: Richard Hoskins [SMTP:healthmaps@home.com] > Sent: Monday, July 09, 2001 2:41 PM > To: waphgis@u.washington.edu > Subject: RE: Zip Codes, ZCTA and areal interpolation. > > I think we need to be very activist concerning geocoding issues - just > because an agency says they won't release data below Zip Code doesn't mean > we should accept that reply if we have serious public health work to do. > If > we need larger scale data, then we should get it - we need to push our > agency management and use the Institutional Review Board process. > > I suggest that "don't have the option" is not the case at all - although > getting another option may not be all that convenient. Public health > people > should demand, and I mean that in the most civil and with the most > non-confrontational attitude possible, but in the end public health > practitioners must get access to the data they need. All public health GIS > folks need to deal with this issue up front. Accept nothing less than what > gets the job done. > > Zip Codes or ZCTA's are not a good spatial entity for public health > analysis. Changing boundaries, inhomogeneous mix of population, small > scale > relative to importance to the public health intervention planning needed; > these are all issues with Zip Codes. Many states collect data at the Zip > Code level only for some important data (in my state, hospital discharge > data) but it is practically usefulness for effective assessment much less > designing an intervention. > > We GIS people have not gotten the message across that Zip Codes are for > delivering the mail, not for delivering public health services. > > If health record sources, in fact, have the address level data, then we > should push them to adopt policies that allow access to this data when it > is > the differences between an effective intervention and one that wastes > public > money and does not serve the people that need it. > > Richard Hoskins > > > -----Original Message----- > From: WAPHGIS-owner@u.washington.edu > [mailto:WAPHGIS-owner@u.washington.edu]On Behalf Of Susan Clemens > Sent: Monday, July 09, 2001 1:04 PM > To: waphgis@u.washington.edu > Subject: RE: Zip Codes, ZCTA and areal interpolation. > > > > > > ---------- > > From: Susan Clemens[SMTP:S-CLEMENS@WILDMAIL.COM] > > Sent: Monday, July 09, 2001 1:03:30 PM > > To: waphgis@u.washington.edu > > Subject: RE: Zip Codes, ZCTA and areal interpolation. > > Auto forwarded by a Rule > > > I have been skeptical of zip codes and/or ZCTA for some time now. > Unfortunately, I am usually analyzing data collected by another > agency so don't have the option of requesting more specific geographic > information. Often a zip code is all that is collected or all that > can be released due to patient confidentiality issues. > > I agree with the observation that zip codes are not consistent through > time. > As I understand it, perimeter changes are the norm when > designating new zip codes. Also, zip + 4 numbers change more frequently > than zip code perimeters and often have more to do with > postal carrier staffing and routes vs population. Lastly, the ZCTA for > the > 1990 Census were developed using a different methodology > than the 2000 ZCTA. Even if you are lucky enough to be in an area with no > new zip codes you cannot compare 1990 and 2000 ZCTA > data. > > So, where does this leave us? Is commercial zip code level data any more > reliable that the ZCTA? Is any zip code level analysis for > health valid given the constraints mentioned? > > Susan Clemens > Humboldt Co Dept of Public Health > > > > ---- Begin Original Message ---- > From: fpb01@health.state.ny.us > Sent: Thu, 5 Jul 2001 15:44:38 -0400 > To: waphgis@u.washington.edu > Subject: RE: Zip Codes, ZCTA and areal interpolation. > > > I believe that ZCTAs were created for the exact purposes given in > Richard's > original posting: to provide an easier way to deal with the mass of data > that is geocoded to zip code only, and to provide a standard (and free) > base map on which to map this data. > > ZCTAs are probably good enough for many purposes, such as marketing > applications. They should also be good enough for certain kinds of > proportional analysis. For example, you can probably safely compare a > variable such as % smoking from a zip code-based survey with % completed > high school from ZCTA. When it comes to using ZCTAs for calcuating > incidence and mortality rates, though, I am pessimistic. > > Frank Boscoe > NYS Department of Health > > > > > > "Richard Hoskins" @u.washington.edu on 07/05/2001 > 03:12:24 PM > > Please respond to waphgis@u.washington.edu > > Sent by: WAPHGIS-owner@u.washington.edu > > > To: > cc: > Subject: RE: Zip Codes, ZCTA and areal interpolation. > > > Frank: What was the purpose of the census bureau's developing the ZCTAs? > > Dick H > > -----Original Message----- > From: WAPHGIS-owner@u.washington.edu > [mailto:WAPHGIS-owner@u.washington.edu]On Behalf Of > fpb01@health.state.ny.us > Sent: Thursday, July 05, 2001 12:00 PM > To: waphgis@u.washington.edu > Subject: Re: Zip Codes, ZCTA and areal interpolation. > > > I believe that conversion from Zip Codes to ZCTAs is, unfortunately, more > than just an areal interpolation problem. The two entities are not the > same > thing - they differ along the edges. On a road that forms the boundary of > a > zip code, both sides of the road may be in the same Zip Code. This is > reasonable and facilitates the delivery of the mail. But the two sides of > the road will be in different census blocks and hence different ZCTAs > (since ZCTAs are built from census blocks). In heavily populated areas, > the distinction is almost negligible, but not in rural areas. In fact, the > census produced a graph which shows that zip code-ZCTA agreement is almost > perfect in zip codes with more than 15,000 addresses, but under 80% where > there were fewer than 250 addresses. > > In terms of health mapping, if a nursing home or hospital or other special > type of address falls on a zip boundary, its entire caseload could be > assigned to the wrong ZCTA, resulting in substantial error even in a > heavily populated area. > > Frank Boscoe > NYS Department of Health > > > > > > > ---- End Original Message ---- > > > > Care2 make the world greener! > http://www.care2.com - Get your Free e-mail account that helps save > Wildlife! > .