From: Diego Vázquez <dvazquez_at_lab.cricyt.edu.ar>

Date: Tue 16 May 2006 - 01:52:52 EST

number of obs: 120, groups: Patient, 24

Time:Drugb 0.064 0.000 -0.707 -0.335 -0.167 Time:Drugp 0.064 0.000 -0.707 -0.167 -0.333 0.500

> anova(fm1)

Analysis of Variance Table

Time:Drug 2 143.17 71.58

Date: Tue 16 May 2006 - 01:52:52 EST

Dear list members,

I am new to R and to the R-help list. I am trying to perform a mixed-model analysis using the lmer() function. I have a problem with the output anova table when using the anova() function on the lmer output object: I only get the numerator d.f., the sum of squares and the mean squares, but not the denominator d.f., F statistics and P values. Below is a sample output, following D. Bates' SASmixed example in his paper "Fitting linear mixed models in R" (R-News 5: 27-30).

By reading the R-help archive, I see that this problem has come up before (e.g., http://tolstoy.newcastle.edu.au/R/help/06/04/25013.html). What I understand from the replies to this message is that this incomplete output results from some unresolved issues with lmer, and that it is currently not possible to use it to obtain full anova statistics. Is this correct? And is this still unresolved? If so, what is the best current alternative to conduct a mixed model analysis, other than going back to SAS?

I would greatly appreciate some help.

Diego

Example using SASmixed "HR" data (see D. Bates, "Fitting linear mixed models in R", R-News 5: 27-30)

> data("HR",package="SASmixed")

> library(lme4)

Loading required package: Matrix

Loading required package: lattice

The following object(s) are masked from package:Matrix :

Data: HR AIC BIC logLik MLdeviance REMLdeviance 788.6769 810.9768 -386.3384 791.8952 772.6769 Random effects: Groups Name Variance Std.Dev. Patient (Intercept) 44.541 6.6739 Residual 29.780 5.4571

number of obs: 120, groups: Patient, 24

Fixed effects:

Estimate Std. Error t value

(Intercept) 33.96209 9.93059 3.4199 baseHR 0.58819 0.11846 4.9653 Time -10.69835 2.42079 -4.4194 Drugb 3.38013 3.78372 0.8933 Drugp -3.77824 3.80176 -0.9938 Time:Drugb 3.51189 3.42352 1.0258 Time:Drugp 7.50131 3.42352 2.1911 Correlation of Fixed Effects: (Intr) baseHR Time Drugb Drugp Tm:Drgb baseHR -0.963 Time -0.090 0.000 Drugb -0.114 -0.078 0.237 Drugp -0.068 -0.125 0.236 0.504

Time:Drugb 0.064 0.000 -0.707 -0.335 -0.167 Time:Drugp 0.064 0.000 -0.707 -0.167 -0.333 0.500

> anova(fm1)

Analysis of Variance Table

Df Sum Sq Mean Sq baseHR 1 745.99 745.99 Time 1 752.86 752.86 Drug 2 86.80 43.40

Time:Drug 2 143.17 71.58

-- Diego Vázquez Instituto Argentino de Investigaciones de las Zonas Áridas Centro Regional de Investigaciones Científicas y Tecnológicas CC 507, (5500) Mendoza, Argentina http://www.cricyt.edu.ar/interactio/dvazquez/ ______________________________________________ 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.htmlReceived on Tue May 16 01:59:35 2006

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