Hey there
I am estimating a multilevel model using lmer.  I have 5 imputed datasets so
I am using mitools to pool the estimates from the 5
>
>  datasets.  Everything seems to work until I try to use
> MIcombine to produced pooled estimates.  Does anyone have any suggestions?  The betas and the standard errors were extracted with no problem so everything seems to work smoothly up until that point.
>
>
> Program
> #Read data
> data.dir<-system.file("dta",package="mitools")
> files.imp<-imputationList(lapply(list.files(data.dir,
> pattern="imp.\\.dta", full=TRUE), read.dta))
>
> #estimate model over each imputed dataset
> model0<-with(files.imp,lmer( erq2tnc ~1+trt2+nash+wash+male+coh2+coh3+(1 |
> sitebeth)))
> #extract betas and standard errors
> betas<-MIextract(model0,fun=coef)
> vars<-MIextract(model0,fun=vcov)
> #Combine the results
> summary(MIcombine(betas,vars))
>
> Error in cbar + results[[i]] : non-numeric argument to binary operator
> Error in summary(MIcombine(betas, vars)) :
> error in evaluating the argument 'object' in selecting a method for
> function 'summary'



Thanks
Beth

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