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Date:         Wed, 7 Oct 2009 10:53:11 -0400
Reply-To:     Peter Flom <peterflomconsulting@mindspring.com>
Sender:       "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From:         Peter Flom <peterflomconsulting@MINDSPRING.COM>
Subject:      Re: predicted probabilities in logistic model
Comments: To: ellen <ellenstats@GMAIL.COM>
Content-Type: text/plain; charset=UTF-8

ellen <ellenstats@GMAIL.COM> wrote >I have a logistic regression model containing several co-variates. I now >wish to estimate the expected number of events for a variable that is not >in the model but is in my data set. Can I simply add up the predicted >probabilities for the additional variable and if so how do I obtain the >confidence interval, can I sum these too?? > >Many thanks for any help you can give.

Do you mean an additional observation? I don't see how this could work with additional variables.

If you do mean observations, then have you seen example 51.15 in the SAS/Stat documentation? Title is "scoring data sets with the score statement".

First, run something ala this <<<< ods graphics on; proc logistic data=Crops plots(only)=effect(x=x3); model Crop=x1-x4 / link=glogit; score out=Score1; run; ods graphics off; >>>

then <<< proc logistic inmodel=sasuser.CropModel; score data=Crops out=Score3; run; >>>

HTH

Peter

Peter L. Flom, PhD Statistical Consultant Website: www DOT peterflomconsulting DOT com Writing; http://www.associatedcontent.com/user/582880/peter_flom.html Twitter: @peterflom


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