Hi,
I use the package "nlme" to fit linear regression on data that has 27
groups (subjects). The following is my scripts.
lw <- groupedData( y ~ x | group, data =
read.table("lw.d",header=T))
lw1 <- lme(y~x,data=lw,random= ~x | group)
Everaything o.k. up to this point. However, the next one,
lw2 <- lme(y~x+sex,data=lw,random= ~x | group),
where sex is classification factor with M=male and F=female, gives the
following message:
Error in MEEM(object, conLin, control$niterEM) :
Singularity in backsolve at level 0, block 1
Is any fix to this problem?
Cheers!
Han
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