From: Robert Bagchi <bagchi.r_at_gmail.com>

Date: Fri 23 Sep 2005 - 05:51:45 EST

bm.surv$death<-4-bm.surv$survival

227.0558 239.6218 -107.5279 215.0558

Random effects:

Groups Name Variance Std.Dev. table (Intercept) 1.8158e-09 4.2613e-05 Residual 3.6317e+00 1.9057e+00

# of obs: 60, groups: table, 10

Date: Fri 23 Sep 2005 - 05:51:45 EST

I'm using R 2.1.1 on windows XP and lme4 0.98-1

Any help will be much appreciated.

###############################

The data are somewhat like this

house=rep(1:10, each=6), light=rep(c("h", "l"), each=6, 5), species=rep(c("sl", "hn"), each=3, 10), damage=rep(c(0,.1,.25), 20) ) bm.surv$survival<-ifelse(bm.surv$light=="h", rbinom(60, 4, .9), rbinom(60, 4, .6)) # difference in probablility should ensure alight effect

bm.surv$death<-4-bm.surv$survival

# fitting the model

m1<-lmer(cbind(survival, death)~light+species+damage+(1|house),
data=bm.surv, family="quasibinomial")

summary(m1) # suggests that light is very significant Generalized linear mixed model fit using PQL

Formula: cbind(survival, death) ~ light + species + damage + (1 | table) Data: bm.surv Family: quasibinomial(logit link) AIC BIC logLik deviance

227.0558 239.6218 -107.5279 215.0558

Random effects:

Groups Name Variance Std.Dev. table (Intercept) 1.8158e-09 4.2613e-05 Residual 3.6317e+00 1.9057e+00

# of obs: 60, groups: table, 10

Fixed effects:

Estimate Std. Error DF t value Pr(>|t|)

(Intercept) 2.35140 0.36832 56 6.3841 3.581e-08 *** lightl -1.71517 0.33281 56 -5.1535 3.447e-06 *** speciessl -0.57418 0.30085 56 -1.9085 0.06145 . damage 1.49963 1.46596 56 1.0230 0.31072

--- Signif. codes: 0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1 Correlation of Fixed Effects: (Intr) lightl spcssl lightl -0.665 speciessl -0.494 0.070 damage -0.407 -0.038 -0.017 anova(m1) # very low F value for light, corresponding to p values approaching 1 Analysis of Variance Table Df Sum Sq Mean Sq Denom F value Pr(>F) light 1 0.014 0.014 56.000 0.0018 0.9661 species 1 0.002 0.002 56.000 0.0002 0.9887 damage 1 0.011 0.011 56.000 0.0014 0.9704 -- Robert Bagchi Animal & Plant Science Alfred Denny Building University of Sheffield Western Bank Sheffield S10 2TN UK t: +44 (0)114 2220062 e: r.bagchi@sheffield.ac.uk bagchi.r@gmail.com http://www.shef.ac.uk/aps/apsrtp/bagchi-r ______________________________________________ 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 Fri Sep 23 06:00:42 2005

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