Schizophrenia data from a randomized controlled trial with patients assigned to either drug or placebo group. "Severity of Illness" was measured, at weeks 0,1,...6, on a four category ordered scale: 1. normal or borderline mentally ill, 2. mildly or moderately ill, 3. markedly ill, and 4. severely or among the most extremely ill. Most of the observations where made on weeks 0,1,3, and 6.
data(schizo)
A data frame with 1603 observations on 437 subjects. Four numerical vectors contain information on
id
patient ID.
y
ordinal response on a 4 category scale.
trt
treatment indicator: 1 for drug, 0 for placebo.
wk
week.
Hedeker, D. and Gibbons, R. (2006). Longitudinal Data Analysis. Wiley, Palo Alto, CA.