\HeaderA{Chem97}{Scores on A-level Chemistry in 1997}{Chem97}
\keyword{datasets}{Chem97}
\begin{Description}\relax
Scores on the 1997 A-level Chemistry examination in Britain.  Students
are grouped into schools within local education authories.  In
addition some demographic and pre-test information is provided.
\end{Description}
\begin{Usage}
\begin{verbatim}data(Chem97)\end{verbatim}
\end{Usage}
\begin{Format}\relax
A data frame with 31022 observations on the following 8 variables.
\describe{
\item[lea] Local Education Authority - a factor
\item[school] School identifier - a factor
\item[student] Student identifier - a factor
\item[score] Point score on A-level Chemistry in 1997
\item[gender] Student's gender
\item[age] Age in month, centred at 222 months or 18.5 years
\item[gcsescore] Average GCSE score of individual.
\item[gcsecnt] Average GCSE score of individual, centered at mean.
}
\end{Format}
\begin{Details}\relax
This data set is relatively large with 31,022 individuals in 2,280
schools.  Note that while this is used, illustratively, to fit Normal
response models, the distribution of the response is not well
described by a Normal distribution.
\end{Details}
\begin{Source}\relax
\url{http://multilevel.ioe.ac.uk/softrev/chem97.html}
\end{Source}
\begin{References}\relax
Yang, M., Fielding, A. and Goldstein, H. (2002). Multilevel ordinal
models for examination grades (submitted to \emph{Statistical Modelling}).
\end{References}
\begin{Examples}
\begin{ExampleCode}
str(Chem97)
summary(Chem97)
(fm1 <- lmer(score ~ (1|school) + (1|lea), Chem97))
(fm2 <- lmer(score ~ gcsecnt + (1|school) + (1|lea), Chem97))
\end{ExampleCode}
\end{Examples}

