On Fri, May 02, 2008 at 03:06:31PM -0500, Giovanni Petris wrote: > > Hello, > > I posted a question yesterday but I got no replies, so I'll try to > reformulate it in a more concise way. > > I have the following data, summarizing approval ratings on two > different surveys for a random sample of 1600 individuals: > > > ## Example: Ratings of prime minister (Agresti, Table 12.1, p.494) > > rating <- matrix(c(794, 86, 150, 570), 2, 2) > > dimnames(rating) <- list(First = c("approve", "disapprove"), > + Second = c("approve", "disapprove")) > > rating > Second > First approve disapprove > approve 794 150 > disapprove 86 570 > > I would like to fit a logit model with approve/disapprove as response, > survey (first/second) as a fixed effect, and subject as a random > effect. > > 1) Is it possible to fit such a model directly using "lmer"? > > or > > 2) Should I unroll the table above into a dataframe containing also > fictitious subject id's? If this is the case, what is a clean way > of doing it?
Unroll it. Asking for a "clean" way to do something is a disincentive because it implies that you know how to do it but not cleanly. In the future I would suggest that you do one of two things a) post your on dirty version and ask for a cleaner one, or b) just ask for something that works. Something like ... ratings <- data.frame( response = c( rep(c(1,1), 794), rep(c(1,0), 150), rep(c(0,1), 86), rep(c(0,0), 570)), time = rep(c(1,2), 1600), subject=rep(1:1600, each=2)) test.lmer <- lmer(response ~ time + (1|subject), data=ratings, family=binomial) but I don't know if you think that's clean or not. Andrew > Thank you in advance, > Giovanni Petris > > -- > > Giovanni Petris <[EMAIL PROTECTED]> > Associate Professor > Department of Mathematical Sciences > University of Arkansas - Fayetteville, AR 72701 > Ph: (479) 575-6324, 575-8630 (fax) > http://definetti.uark.edu/~gpetris/ > > ______________________________________________ > 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. -- Andrew Robinson Department of Mathematics and Statistics Tel: +61-3-8344-6410 University of Melbourne, VIC 3010 Australia Fax: +61-3-8344-4599 http://www.ms.unimelb.edu.au/~andrewpr http://blogs.mbs.edu/fishing-in-the-bay/ ______________________________________________ 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.