Dear all, 1. How do I compute the fixed-effects var-cov matrix from a GLMM object (lme4 package) fitted with the Laplace method? details: the vcov method for GLMM objects does not seem to work in this case: returns a 0 * 0 matrix: > fm1 <- GLMM(immun ~ kid2p + mom25p + ord, + family = binomial, data = guImmun, random = ~ 1 | comm, method = "Laplace") Using optimizer nlm > fm1 Generalized Linear Mixed Model Family: binomial family with logit link Fixed: immun ~ kid2p + mom25p + ord Data: guImmun log-likelihood: -1400.842 Random effects: Groups Name Variance Std.Dev. comm (Intercept) 0.61621 0.78499 # of obs: 2159, groups: comm, 161 Estimated scale (compare to 1) 0.9702206 Fixed effects: Estimate Std. Error z value Pr(>|z|) (Intercept) -0.970969 0.162467 -5.9764 2.281e-09 kid2pY 0.991837 0.119242 8.3178 < 2.2e-16 mom25pY -0.052423 0.129561 -0.4046 0.6858 ord23 -0.094408 0.140715 -0.6709 0.5023 ord46 0.040217 0.167089 0.2407 0.8098 ord7p 0.013805 0.206611 0.0668 0.9467 (Intercept) kid2pY mom25pY ord23 ord46 ord7p [1,] -0.970969 0.9918369 -0.05242273 -0.09440838 0.04021697 0.01380546 > vcov(fm1) <0 x 0 matrix> ############# 2. Is it relevant and efficient to use this var-cov matrix to perform Wald-like tests for the significance of one or more fixed effects ? version information: # R _ platform i386-pc-mingw32 arch i386 os mingw32 system i386, mingw32 status major 2 minor 0.0 year 2004 month 10 day 04 language R # lme4 Package: lme4 Version: 0.6-9 Date: 2004-10-04 # Matrix Package: Matrix Version: 0.8-15 Date: 2004-10-02 ######### Thanks, Renaud -- Dr Renaud Lancelot, v??t??rinaire C/0 Ambassade de France - SCAC BP 834 Antananarivo 101 - Madagascar e-mail: renaud.lancelot at cirad.fr tel.: +261 32 40 165 53 (cell) +261 20 22 665 36 ext. 225 (work) +261 20 22 494 37 (home)