Dear Statalist,
I am analyzing individuals in peer groups for a dichotomous outcome. Initially I was repeating an analysis that a colleague had completed in SAS (a generalized linear mixed model - PROC GLMMIX in SAS - with "peer group" included as a random variable), and I confirmed my approach against his work using the following syntax:
-xtlogit depvar indicator1 indicator2 indicator3, re i(peergroup)-
However, when I try to generate predicted values from my model, the mean predicted values are *negative*.
-predict estp if e(sample), xb nooffset-
The trends are as I would expect (that the predicted value is more negative, or smaller, for my intervention group than for my control group; also confirmed graphically), but despite having explored other prediction options, I haven’t been able to produce positive predicted values. A Statalist archives posting discusses a similar problem of trying to fit a linear model to nonlinear data, but I am not working with a linear outcome or covariate.
Thank you for your consideration,
Elizabeth Mumford
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