[R] linear mixed-effects model

[Han Lai]

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

-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-
r-help mailing list -- Read http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html
Send "info", "help", or "[un]subscribe"
(in the "body", not the subject !)  To: r-help-request at stat.math.ethz.ch
_._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._