search for: unbalanac

...erEM) : Singularity in backsolve at level 0, block 1 x is a numeric vector containing 194 observations. f1 is a factor vector containing two levels, and f2 is a different factor vector containing 5 different levels. R1 is a another factor vector containing 13 different levels, and it is again, unbalanaced. f1, f2 and r1 are unbalanced, but I can't do anything about it. The data comes from wild-caught samples and not from a nice, neat experiment. If I change the model specification slightly removing the interaction term (e.g. anova(lme(x ~ f1 + f2, data=m, random=~1|r1)) ), then lme proceeds...