i am aware of this but i don't know why. On Thu, 16 Jun 2005 10:31:25 +0200 Emmanuel Tillard <[EMAIL PROTECTED]> wrote:
> Dear R users > > I encounter a problem when i perform a generalized linear mixed model (binary > data) with the lmer function (package lme4) > with R 2.1.0 on windows XP and the latest version of package "lme4" (0.96-1) > and "matrix" (0.96-2) > both options "PQL" and "Laplace" for the method argument in lmer function > gave me the same results (random and fixed effects estimates, standard error > and p.values). However, Loglikelihood and deviance are different. > > here is an example reproduced with the bacteria data set available in the > MASS package: > > library(lme4) > library(MASS) > > data(bacteria) > bacteria$week2 <- as.factor(ifelse(bacteria$week <=2, 0, 1)) > model.PQL <- lmer(y ~ trt + week2 + (1 | ID), family = binomial, data = > bacteria, method ="PQL") > model.Laplace <- lmer(y ~ trt + week2 + (1 | ID), family = binomial, data = > bacteria, method ="Laplace") > > model.PQL > model.Laplace > > > model.PQL > Generalized linear mixed model fit using PQL > Formula: y ~ trt + week2 + (1 | ID) > Data: bacteria > Family: binomial(logit link) > AIC BIC logLik deviance > 152.443 138.8685 -80.2215 160.443 > Random effects: > Groups Name Variance Std.Dev. > ID (Intercept) 3.2721 1.8089 > # of obs: 220, groups: ID, 50 > > Estimated scale (compare to 1) 0.7800484 > > Fixed effects: > Estimate Std. Error z value Pr(>|z|) > (Intercept) 3.41227 0.65884 5.1792 2.228e-07 *** > trtdrug -1.24743 0.81841 -1.5242 0.1274555 > trtdrug+ -0.75440 0.82009 -0.9199 0.3576229 > week21 -1.60737 0.45527 -3.5306 0.0004146 *** > --- > Signif. codes: 0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1 > > > model.Laplace > Generalized linear mixed model fit using Laplace > Formula: y ~ trt + week2 + (1 | ID) > Data: bacteria > Family: binomial(logit link) > AIC BIC logLik deviance > 304.9488 291.3743 -156.4744 312.9488 > Random effects: > Groups Name Variance Std.Dev. > ID (Intercept) 3.2721 1.8089 > # of obs: 220, groups: ID, 50 > > Estimated scale (compare to 1) 0.7800484 > > Fixed effects: > Estimate Std. Error z value Pr(>|z|) > (Intercept) 3.41227 0.65884 5.1792 2.228e-07 *** > trtdrug -1.24743 0.81841 -1.5242 0.1274555 > trtdrug+ -0.75440 0.82009 -0.9199 0.3576229 > week21 -1.60737 0.45527 -3.5306 0.0004146 *** > --- > Signif. codes: 0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1 > > is anybody else aware of this? or did I forget something important ? > > Many thanks for your help. > > -- > Emmanuel Tillard > Veterinaire > CIRAD-EMVT > Unite de recherche 18 > > UMR868 Elevage des Ruminants en Regions Chaudes (ERRC) > Campus ENSA-INRA > 2 place Viala > 34060 Montpellier cedex 1 > > tel: 0499612265 (fixe) > 0633850598 (gsm) > fax: 0467545694 > e-mail: [EMAIL PROTECTED] > > ______________________________________________ > R-help@stat.math.ethz.ch mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html ______________________________________________ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
