[R] linear hypothesis test in gls model

[Tine Huyghe]

Dear all,

For analysis of a longitudinal data set with fixed measurement in time I built a gls model (nlme). For testing hypotheses in this model I used the linear.hypothesis function from the car package. A check with the results obtained in SAS proc MIXED with a repeated statement revealed an inconsistency in the results. The problem can be that the linear.hypothesis function (1) only gives the asymptotic chi square test and/or (2) only uses the residual error. Is there another solution to testing linear hypotheses in a gls model?

Thanks in advance