Hi all, I was trying to fit a Gamma hierarchical model using "glmer", but got weird error message that I could not understand. On the other hand, a similar call to the glmmPQL leads to results that are close to what I expect. I also tried to change tha "nAGQ" argument in "glmer", but it did not solve the problem. The model I was fitting has a simple structure - one hierarchy and one offset, and I did not expect "glmer" to fail on this simple data set. Did I specify something wrong here? I appreciate any help. Thanks in advance.
############################################################# ## Code to fit the model ############################################################# library(MASS) library(lme4) address <- "http://instruction.bus.wisc.edu/jfrees/jfreesbooks/Longitudinal%20and%20Panel%20Data/Book/Data/TXTData/WorkerC.txt"; wc <- read.table(address,header=T) # clean data cl <- unique(wc$CL[wc$LOSS==0]) wc2 <- subset(wc, !(CL %in% cl) ) # fit model fit1 <- glmmPQL(LOSS~ YR+offset(log(PR)), random=~1|CL,family=Gamma(link="log"), data=wc2) fit2 <- glmer(LOSS~ (1|CL) + YR+offset(log(PR)), family=Gamma(link="log"), data=wc2) ############################################################# ## Results of fit1 and fit2 ############################################################# > fit1 Linear mixed-effects model fit by maximum likelihood Data: wc2 Log-likelihood: NA Fixed: LOSS ~ YR + offset(log(PR)) (Intercept) YR -4.2830507147 0.0005085944 Random effects: Formula: ~1 | CL (Intercept) Residual StdDev: 0.8313193 0.5346455 Variance function: Structure: fixed weights Formula: ~invwt Number of Observations: 700 Number of Groups: 100 > fit2 Error in asMethod(object) : matrix is not symmetric [1,2] Wayne (Yanwei) Zhang Statistical Research CNA Email: yanwei.zh...@cna.com<mailto:yanwei.zh...@cna.com> NOTICE: This e-mail message, including any attachments and appended messages, is for the sole use of the intended recipients and may contain confidential and legally privileged information. If you are not the intended recipient, any review, dissemination, distribution, copying, storage or other use of all or any portion of this message is strictly prohibited. If you received this message in error, please immediately notify the sender by reply e-mail and delete this message in its entirety. [[alternative HTML version deleted]] ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
