[R] linear mixed-effects model

Han Lai hlai at whsun1.wh.whoi.edu
Tue Oct 2 00:04:00 CEST 2001


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?


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