% \VignetteIndexEntry{Arthritis - Cumulative Logit Model}
% \VignetteDepends{VGAM}
%\VignetteEngine{knitr::knitr}
%\VignetteEncoding{UTF-8}
    \documentclass[a4paper]{article}

\title{Arthritis - Cumulative Logit Model}

\begin{document}

\maketitle

<<echo=FALSE,eval=FALSE>>=
options(width=80)
@


A simple data frame for the arthritis data is created with the numbers given for the individual cells.

<<eval=FALSE>>=
arthritis <- data.frame(drug=c(rep("new agent", 24+37+21+19+6), 
rep("active control", 11+51+22+21+7)), 
assessment=c(rep(1,24), rep(2,37), rep(3,21), rep(4,19), rep(5,6), rep(1,11), 
rep(2,51), rep(3,22), rep(4,21), rep(5,7)))
@

<<eval=FALSE>>=
library(VGAM)
@

Now a cumulative model is fitted.

<<eval=FALSE>>=
cumart <- vglm(assessment ~ drug, family=cumulative(parallel=TRUE, link="logitlink"), 
              data=arthritis)
@

<<eval=FALSE>>=
summary(cumart)
@

<<echo=FALSE,eval=FALSE>>=
detach(package:VGAM)
@
\end{document}
