Displaying 1 result from an estimated 1 matches for "covariateb".
Did you mean:
covariates
2003 Jun 23
1
precision matrix for polynomial growth curves
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 pol...