Tagged Questions

13
votes
2answers
2k views

How should mixed effects models be compared and or validated?

How are (linear) mixed effects models normally compared against each other? I know likelihood ratio tests can be used, but this doesn't work if one model is not a 'subset' of the other correct? Is ...
0
votes
1answer
192 views

What is a good academic citation for cross-validation?

I performed a holdout cross-validation analysis on a multilevel model fit. The purpose of this was to show that we didn't have a problem with over-fitting, for which it worked just fine. Now we are ...
2
votes
1answer
477 views

Cross Validation for mixed models?

My colleague and I are fitting a range of linear and nonlinear mixed effect models in R. We are asked to perform cross-validation on the fitted models so that one can verify that the effects observed ...
4
votes
2answers
6k views

How to specify random effects in lme?

I have searched for this online for hours but none of online posts is what I am looking for. My question is very easy to implement in SAS Proc mixed procedure but I am not sure how to do it in lme ...