Dear list, I fitted a linear mixed effects model using lme in R on a relatively large data set. Now I want to extend this model, introducing an additional fixed effect on a subset of the data without altering coefficients estimated on the original dataset. I.e. original model for example: m1 = lme(y~a+b,random=~1|id,data=D) now I want to do something similiar to m2 = update(m1,~.+c,data=d) Where d is a subset of D. The values of the new predictor c are only available for this subset. However, I would like to keep the originally estimated coefficients of the model m1 with regard to predictors a and b. If I use update as described above coefficients for all predictors (a,b,c) are estimated again on the smaller dataset d. Any suggestions on how I can estimate the effect of c while keeping the old coefficient values for a and b? Or is this for some reason a bad idea altogether? Urs
How to extend an existing linear mixed effects model using lme in R?
2 messages · urs, Bert Gunter
You should post this on the mixed models list instead of here: https://stat.ethz.ch/mailman/listinfo/r-sig-mixed-models Cheers, Bert Bert Gunter "The trouble with having an open mind is that people keep coming along and sticking things into it." -- Opus (aka Berkeley Breathed in his "Bloom County" comic strip )
On Tue, Mar 22, 2016 at 2:36 PM, urs <urs at kleinholdermann.de> wrote:
Dear list, I fitted a linear mixed effects model using lme in R on a relatively large data set. Now I want to extend this model, introducing an additional fixed effect on a subset of the data without altering coefficients estimated on the original dataset. I.e. original model for example: m1 = lme(y~a+b,random=~1|id,data=D) now I want to do something similiar to m2 = update(m1,~.+c,data=d) Where d is a subset of D. The values of the new predictor c are only available for this subset. However, I would like to keep the originally estimated coefficients of the model m1 with regard to predictors a and b. If I use update as described above coefficients for all predictors (a,b,c) are estimated again on the smaller dataset d. Any suggestions on how I can estimate the effect of c while keeping the old coefficient values for a and b? Or is this for some reason a bad idea altogether? Urs
______________________________________________ R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.