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Date:         Fri, 14 Mar 2008 14:11:16 -0400
Reply-To:     msz03@albany.edu
Sender:       "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From:         Mike Zdeb <msz03@ALBANY.EDU>
Subject:      Re: segmented regression problem
Content-Type: text/plain;charset=iso-8859-1

Hi ... if you are willing to try something other than SAS, you can use the National Cancer Institute's JOINPOINT software ...

http://srab.cancer.gov/joinpoint/

or SEGREG ...

http://www.waterlog.info/segreg.htm

("Joinpoint Goddess", "SEGREG Goddess", hmmmm.... not as universal as "SAS Goddess")

-- Mike Zdeb U@Albany School of Public Health One University Place Rensselaer, New York 12144-3456 P/518-402-6479 F/630-604-1475

> Help! I am at risk of losing my SAS goddess stature among grad > students! > > I've been asked for SAS help with something out of my area, but which > seems common enough in the literature that hopefully someone on the > list can provide some quick code help. > > When analyzing ovarian follicle growth, an important factor is the > time at which the dominant follicle diverges from the others (follicle > deviation). This has been done by visual observation of plots of the > size of largest two follicles (F1 and F2) against time (deviation is > the time when the lines obviously diverge). A better statistical > approach is desirable. Segmented regression seems to be apropos. > > "Calculated follicle deviation using segmented regression for modeling > diameter differences in cattle" > D. R. Bergfelt, L. H. Segoc, M. A. Bega, and O. J. Ginther > Theriogenology, Volume 59, Issue 8, 15 April 2003, Pages 1811-1825 > Is basically what I'm after, but I don't know how to get it out of > PROC REG. > > So with data like: > > subject > time > F1-F2 (difference in size of F1 and F2) > > How do I get to a calculated time of deviation for each subject? > > Thanks, > Ashley > >


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