nlschools                package:MASS                R Documentation

Eighth-Grade Pupils in the Netherlands

Description:

     Snijders and Bosker (1999) use as a running example a study of
     2287 eighth-grade pupils (aged about 11) in 132 classes in 131
     schools in the Netherlands.  Only the variables used in our
     examples are supplied.

Usage:

     data(nlschools)

Format:

     This data frame contains 2287 rows and the following columns:

     'lang' language test score

     'IQ' Verbal IQ

     'class' class ID

     'GS' Class size: number of eighth-grade pupils recorded in the
          class (there may be others: see 'COMB', and some may have
          been omitted with missing values).

     'SES' Social-economic status of pupil's family.

     'COMB' were the pupils taught in a multi-grade class ('0/1')? 
          Classes which contained pupils from grades 7 and 8 are coded
          '1', but only eighth-graders were tested.

Source:

     Snijders, T. A. B. and Bosker, R. J. (1999) _Multilevel Analysis.
     An Introduction to Basic and Advanced Multilevel Modelling._
     London: Sage.

References:

     Venables, W. N. and Ripley, B. D. (2002) _Modern Applied
     Statistics with S._ Fourth edition.  Springer.

Examples:

     library(nlme)
     nl1 <- nlschools
     attach(nl1)
     classMeans <- tapply(IQ, class, mean)
     nl1$IQave <- classMeans[as.character(class)]
     nl1$IQ <- nl1$IQ - nl1$IQave
     detach()
     cen <- c("IQ", "IQave", "SES")
     nl1[cen] <- scale(nl1[cen], center = TRUE, scale = FALSE)

     nl.lme <- lme(lang ~ IQ*COMB + IQave + SES,
                   random = ~ IQ | class, data = nl1)
     summary(nl.lme)

