Bleeding edge lme4 (or lme4a) plus DF estimation
Joehanes, Roby (NIH/NHLBI) [F] <roby.joehanes at ...> writes:
I discovered a bug on your lme4Eigen's refit function. This is on version 0.9996875-9 (Description revision 169). I hope I got this right. If the original data matrix has some missing data in it, somehow the X and Z matrices (and y column) are correctly trimmed (i.e., the rows with missing data are removed). However, if I fit it with another y column, it reports error due to length mismatch. The error is as follows: Error: length(newresp <- as.numeric(as.vector(newresp))) == length(rr$y) is not TRUE Should I try the latest version and see if this bug has been fixed?
It probably hasn't. It would be very helpful if you could send a small self-contained example to lme4-authors <at> r-forge.wu-wien.ac.at -- we could probably make one up ourselves, but it would be quicker/ more motivational if you did it.
Also, will update method speed up computation if I changed the X (or Z) matrix a little bit by swapping or adding up to three columns (from about 40+ columns)?
Probably not -- refit saves time by (1) starting from previous starting values and (2) not having to rebuild X and Z components. You could do #1 yourself by doing something like setting update(...,start=getME(prevfit,"theta"),...) (I think).