lmer.lmer of the
lme4 R-package. It applies the approximation of the variance-covariance
matrix of variance components according to Giesbrecht & Burns (1985) and uses this
information to approximate the degrees of freedom according to Satterthwaite
(see SAS PROC MIXED documentation option 'CL').
lmerSummary(obj, VarVC = TRUE, terms = NULL, Mean = NULL, cov = FALSE, X = NULL)Giesbrecht, F.G. and Burns, J.C. (1985), Two-Stage Analysis Based on a Mixed Model: Large-Sample Asymptotic Theory and Small-Sample Simulation Results, Biometrics 41, p. 477-486
remlVCA, remlMM