nlschools {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)

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