[R-sig-ME] refit, update and the like

[Juan Pedro Steibel]

Hello everyone,
I have a questions on refitting models using lmer. Some time ago, I 
asked about refitting the same model (X,Z,R) to many responses and was 
pointed at the refit function as a more efficient alternative to just 
running lmer() function iteratively.
My question now is, suppose I want to change only one column from X (say 
replace covariate X1 with covariate X2), is there a faster way that just 
re-fitting the model with lmer. update() does not seem to be working for 
doing that in my case. I can update to drop only one random effect from 
the model but when I try to drop other terms, I get an error message.

Thanks in advance,
JP

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=============================
Juan Pedro Steibel

Assistant Professor
Statistical Genetics and Genomics

Department of Animal Science & 
Department of Fisheries and Wildlife

Michigan State University
1205-I Anthony Hall
East Lansing, MI
48824 USA 

Phone: 1-517-353-5102
E-mail: steibelj at msu.edu