Date:         Mon, 29 Oct 2001 16:26:45 -0600
Reply-To:     wschlech@ktc.com
Sender:       "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From:         Warren Schlechte <wschlech@KTC.COM>
Subject:      dscale or pscale: Proc Genmod
Content-Type: text/plain; charset="iso-8859-1"

In Genmod, you can specify overdispersed model errors with the pscale and
dscale options.  How do you decide which one is the more proper for any
situation?  How does one report results if the results of the hypothesis
tests change depending upon which scale term is used?  For example, in one
model that I examined, the follow were the results:


                Contrast        Estimate        SE        Alpha         Confidence Limits          Chi-Sq       Prob>Chi-Sq
NOSCALE 10K-Control     -1.0151      0.4682
 0.05     -1.9326     -0.0975      4.70        0.0301

DSCALE   10K-Control     -1.0151      0.6818      0.05     -2.3514
0.3212      2.22        0.1365

PSCALE   10K-Control     -1.0151      0.5654      0.05     -2.1233
0.0931      3.22        0.0726

Thanks for your comments.



Warren Schlechte
Heart of the Hills Research Station
HC7 Box 62
Ingram, Texas 78025
Phone:   830.866.3356
Fax:       830.866.3549