Hi there

I am a Masters student at the University of Stellenbosch. I have been using R to analyze the data, using the GLS model, of one of my experiments.
The problem that I am having is that whenever I run my model using:
fit.glsmodel1<-gls(Number~as.factor(Season)+as.factor(Depth)+as.factor(Orientation), data=Number, weights=varPower(), method="ML")

I get the error:
Error in glsEstimate(object, control = control) :    computed "gls" fit is singular, rank 8

I would like to know if anyone can tell me what is causing this error. Any advice will be much appreciated.

Kind regards
Brendan

	[[alternative HTML version deleted]]

