LISTSERV at the University of Georgia
Menubar Imagemap
Home Browse Manage Request Manuals Register
Previous messageNext messagePrevious in topicNext in topicPrevious by same authorNext by same authorPrevious page (April 2012, week 3)Back to main SAS-L pageJoin or leave SAS-L (or change settings)ReplyPost a new messageSearchProportional fontNon-proportional font
Date:   Thu, 19 Apr 2012 11:33:10 -0500
Reply-To:   Warren Schlechte <Warren.Schlechte@TPWD.STATE.TX.US>
Sender:   "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From:   Warren Schlechte <Warren.Schlechte@TPWD.STATE.TX.US>
Subject:   Proc GLIMMIX - Estimate Question
Content-Type:   text/plain; charset="us-ascii"

The following is the coding for a model I have run:

proc glimmix data=data2b ; class ndens tank arch; model out/in = arch ndens days /s dist=binomial link=logit e3 oddsratio; random _residual_; random intercept/subject=tank; output out=binom_pout predicted(ilink noblup) =p resid(ilink noblup)=r; estimate "S125" intercept 1 ndens 1 0 0 arch 1 0/ilink cl; run;

Some items to notice: * ndens, and arch are fixed categorical variables * tank is a random categorical variable * days is a fixed continuous variable * the random residual statement is included to help capture overdispersion in the binomial response.

What I am most interested in is this: Is the estimate statement giving me the predicted value for my first treatment of density and architecture at the average of the variable "days", and averaged across all "tanks"? Is that a correct assumption, and if not, how do I change the code to reflect the "average" conditions.

The reason I ask is, if I use the estimate statement, I get one estimate of the predicted outcome. If instead, I use the output statement, then create the summary statistics of the predicted values, I get a substantially different answer. The value from the estimate statement seems to reflect the estimate when days=0, not at the mean of days.

There is some unbalancedness within the design, but not so severe I would expect to see the differences I see.

Thanks.

Warren Schlechte HOH Fisheries Science Center 5103 Junction Hwy Mt. Home, TX 78058 Phone 830.866.3356 x214 Fax 830.866.3549

Learn how you can help Texas State Parks <http://bit.ly/sVdilb>


Back to: Top of message | Previous page | Main SAS-L page