From espinello@rpmconsulting.com Mon Jan 24 13:00:36 2005 Received: from mxe3.u.washington.edu (mxe3.u.washington.edu [140.142.32.137]) by lists.u.washington.edu (8.13.3+UW05.01/8.13.3+UW05.01) with ESMTP id j0OL0a7b104378 for ; Mon, 24 Jan 2005 13:00:36 -0800 Received: from mail05b.webhosting-verizon.net (mail05b.webhosting-verizon.net [209.238.3.61]) by mxe3.u.washington.edu (8.13.3+UW05.01/8.13.3+UW05.01) with SMTP id j0OL0XES023339 for ; Mon, 24 Jan 2005 13:00:34 -0800 Received: from www.rpmconsulting.com (208.55.49.200) by mail05b.webhosting-verizon.net (RS ver 1.0.95vs) with SMTP id 3-0968897563; Mon, 24 Jan 2005 15:12:44 -0500 (EST) Message-ID: <009301c50251$1f1a21e0$0300a8c0@newrr> From: "E. Spinello" To: Cc: References: <16A0583FB1644E4DB8C0A0265028B6FD026BB65C@nihexchange13.nih.gov> Subject: Re: Census Tract Data Conversions Date: Mon, 24 Jan 2005 12:13:07 -0800 MIME-Version: 1.0 Content-Type: text/plain; format=flowed; charset="iso-8859-1"; reply-type=original Content-Transfer-Encoding: 7bit X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.2180 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.2180 X-Loop-Detect: 1 X-Uwash-Spam: Gauge=IIIIIII, Probability=7%, Report='__C230066_P5 0, __CT 0, __CTE 0, __CTYPE_CHARSET_QUOTED 0, __CT_TEXT_PLAIN 0, __FRAUD_419_BADTHINGS 0, __HAS_MSGID 0, __HAS_MSMAIL_PRI 0, __HAS_X_MAILER 0, __HAS_X_PRIORITY 0, __MIME_VERSION 0, __SANE_MSGID 0' I have accomplished the same thing in the past using the Geographic Correspondence Engine (Geocorr) at CIESIN. The URL is http://plue.sedac.ciesin.columbia.edu/plue/geocorr/. It will allow you to create an equivilancy file that weights variables from 1990 for conversion to 2000, or vice versa. Additionally, you could use any GIS that provides a spatial overlay capability to accomplish the same thing. Elio Spinello ----------------------------------------------- Elio Spinello, MPH, Ed.D. California State University, Northridge 18111 Nordhoff Street Northridge, CA 91311 http://wwww.csun.edu/~hchsc018 espinello@csun.edu ----------------------------------------------- "Small print leads to big risk" Ferengi Rules of Acquisition (#8 ----- Original Message ----- From: "Stinchcomb, David (NIH/NCI)" To: Cc: Sent: Monday, January 24, 2005 11:49 AM Subject: Census Tract Data Conversions > We are looking into ways to convert data based on 1990 census tracts into > data based on 2000 census tracts. With the aid of a GIS, we know we could > do > the conversion by assigning values proportional to the area of the census > tract pieces (the intersection of the two layers). However, this assumes > that the population is uniformly distributed across space and we are not > comfortable with this assumption. > > There is a set of "Census Tract Relationship Files" put out by the Census > Bureau: > http://www.census.gov/geo/www/relate/rel_tract.html > > These files seem to provide enough information to allow such a conversion > based on the actual population in each piece rather than the area. > > Has anyone used these relationship files to do population-based > conversions > of 1990 census tract data to 2000 census tract data? If so, can you share > any of the procedural details? > > In any case, let me know if you think this would be a useful tool. > > I will summarize responses. > > Thanks, > -- Dave Stinchcomb > Health Statistician / Geographer > National Cancer Institute > StinchcD@mail.nih.gov > 301-594-7251 .