[R] Extracting error terms from an lme object

From: Erlend Birkeland Nilsen <Erlend.Nilsen_at_sue.hihm.no>
Date: Tue 21 Feb 2006 - 19:50:15 EST

Hi all,

I have a problem with extracting the right error terms from an lme-object. The fixed part of the model is quite simple (y~x1*x2, where x1 and x2 are factor variables with two levels), with random intercepts (random=~1|group). As I work with factor variables here, I would like to display this with a barplot (or something like that), with error bars representing the sem or sd of the mean values for each group (i.e. four bars). However, I have not figured out how to extract sem (sd) values for these means, or actually what would be the appropriate error terms to use here. The summary.lme function only provides me with the se for the parameter estimates (intercept and slopes) while I want to display error terms for the different levels. Could this be achieved by setting up an appropriate contrast matrix (or would any of the established contrasts methods work), or is there another way of getting error estimates that I could use in such a figure?

All the best,

Erlend Nilsen

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