Hi,

I have a dataset like this,

> testdata
Grouped Data: expr ~ visit | subject
      expr visit subject
1 6.502782    V1       A
2 6.354506    V1       B
3 6.349184    V1       C
4 6.386301    V2       A
5 6.376405    V2       B
6 6.758640    V2       C
7 6.414142    V3       A
8 6.354521    V3       B
9 6.396636    V3       C

I tried the command
> testresult=lme(expr~visit,data=testdata,random=~visit|subject)

I got the following error message.
Error in MEestimate(lmeSt, grps) : Singularity in backsolve at level 0, block 1
In addition: There were 50 or more warnings (use warnings() to see the
first 50)

Could someone give me some hint on what went wrong?  Thanks.

Donglei Hu


