What does the warning message "1: Singular precision matrix in level -1, block 1" mean?
I get this warning 50+ times when I try to fit the following model lme( response ~ covariateA + poly(covariateB,3), ~poly(covariateB,3)|group ) It's not a small dataset - a set of up to 20 blood pressure readings on just over 2000 people, and I don't get the error message when I try to fit fewer random effects (although I'm not sure whether fitting random effects poly(B,2) with fixed effects poly(B,3) is generally the same as fitting random effects B+B^2 with fixed effects B+B^2+B^3). Sometimes I don't get the error message when I use subsets of the data, but that isn't guaranteed to be the case. If anybody could give me pointers to references for or could answer either question themselves (1. why the error message/what's causing it and 2. fitting random polynomials using poly()) I would be very grateful. ______________________________________________ [EMAIL PROTECTED] mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-help
