On 8/7/07, Daniel Caro <[EMAIL PROTECTED]> wrote: > Dear all, > > I want to estimate a crossed-random-effects model (i.e., measurements, > students, schools) where students migrate between schools over time. > I'm interested in the fixed effects of "SES", "age" and their > interaction on "read" (reading achievement) while accounting for the > sample design. Based on a previous post, I'm specifying my model as: > fm1 <- lmer2(read ~ SES*age +(1| schlid:idl) +(1| schlid), hamburg, > control=list(gradient = FALSE, niterEM = 0)) > where my data is "hamburg" and "idl" and "schlid" are the student and > school ids, respectively. > > (1) Is this the specification I want to estimate to obtain those > effects while accounting for...? I'm not sure about the grouping > variables specification. > > If not, how should I specify my model? I reviewed Baltes (2007) > "Linear mixed model implementation" and learned how to detect if my > design is nested or crossed, but not how to specify my model once I > know it is crossed as in my case. > > If the previous specification is correct, (2) why do I get this error message? > > Error in lmerFactorList(formula, fr$mf, !is.null(family)): number of > levels in grouping factor(s) 'idl:schlid' is too large > In addition: Warning messages: > 1: numerical expression has 30113 elements: only the first used in: idl:schlid > 2: numerical expression has 30113 elements: only the first used in: idl:schlid > > My design consists of 14,047 students, 200 schools and 33,011 obs. > > I could, however, run this model: > > fm2 <- lmer2(read ~ SES*age + (1|idl) +(1|schlid), hamburg) > > But I guess it does not account for the crossed design. Does it?
Yes, it does account for the crossed design. > I'm not an statistician and am using lmer() and R for the first time > today. In other words, I sincerely apologize for the very naïve > question. But I would really like to estimate this model soundly and I > can't with the software I am familiar with > > Any advice or references are very much appreciated. > > All the best, > Daniel > > ______________________________________________ > 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 > and provide commented, minimal, self-contained, reproducible code. > ______________________________________________ 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 and provide commented, minimal, self-contained, reproducible code.
