Kostenko, Olga <O.Kostenko <at> nioo.knaw.nl> writes: > I have a question about the output of linear mixed model fitted in R > using nlme package. In particular, what are the t-values that are given > in an output, how are they calculated and based on what test? I guess it > cannot be a simple Student t-test, otherwise how can the simple Student > t-test test for significance of interactions, right? I cannot find this > information in any of R help resources on linear-mixed models and I also > checked few books.
The t-statistics are the ratio of the previously quoted Value (parameter estimate) and Std.Error columns; the p value is a 2-sided test against the null hypothesis that this t-statistic is drawn from a standard t distribution with "DF" degrees of freedom, i.e. 2*pt(abs(tstat),df=DF,lower.tail=FALSE) You will find this referred to in the literature as a "Wald test". For more information the best reference is Pinheiro and Bates 2000 (Springer) ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
