[R-sig-ME] complex cross classified model

[Sven De Maeyer]

Hi all,

I'm analysing data with the following structure:828 students nested  
within 138 schools. Every student supplied 13 items (wright/wrong).  
The data set contains 13 lines for every student. I consider a random  
effect for items as well. The model was set-up as follows, with the  
resulting output are presented at the bottom. My question now is  
whether setting-up the model like this implies that ITEM and IDSTUD  
are crossed and IDSTUD's are nested within SCHOOLS. Or do I make a  
mistake here?

 > Model1<-lmer(SCORE~1+(1|IDSCHOOL)+(1|IDSCHOOL:IDSTUD)+(1| 
ITEM),data=Items, family=binomial)
 > summary(Model1)
Generalized linear mixed model fit using Laplace
Formula: SCORE ~ 1 + (1 | IDSCHOOL) + (1 | IDSCHOOL:IDSTUD) + (1 | ITEM)
    Data: Items
  Family: binomial(logit link)
    AIC   BIC logLik deviance
  10761 10790  -5376    10753
Random effects:
  Groups          Name        Variance Std.Dev.
  IDSCHOOL:IDSTUD (Intercept) 0.772882 0.87914
  IDSCHOOL        (Intercept) 0.076846 0.27721
  ITEM            (Intercept) 1.727892 1.31449
number of obs: 10764, groups: IDSCHOOL:IDSTUD, 828; IDSCHOOL, 138;  
ITEM, 13

Estimated scale (compare to  1 )  0.9272256

Fixed effects:
             Estimate Std. Error z value Pr(>|z|)
(Intercept)   0.8852     0.3676   2.408   0.0160 *
---

With kind regards,

Sven De Maeyer
University of Antwerp