@michellemabelle wrote:
Ok, I'll avoid stepwise then. Then my issue becomes doing variable selection with multiple imputation. Looking elsewhere on the boards, I've found someone suggest to perform variable selection on a single imputation, and then run that model on all the other imputations using mi analyze to pool coeffients and odds ratios, but I am confused as to how to implement this, or if this is statistically sound. Thank you very much!
I think doing variable selection on a single imputation and then using that model thereafter on the other imputations is questionable. That's my opinion. I note that I don't have any experience with that method.
But whatever you come up with, I'm probably not going to like if it involves variable selection; so you might as well come up with something that YOU like and YOU can feel good about.
By the way, how are you doing the imputation in PROC MI? If you are using the EM method, that would make everything feel better to me, as then the different imputations ought to produce somewhat similar models, although the horrors of stepwise could still cause trouble. You see, the EM method ought to (across multiple imputations) result in data that has roughly the same covariance matrix, and thus ought to produce roughly the same Logistic regression models, but no guarantees either. If you're not using EM here, then I don't like it.
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