Disease progression in an alzheimer's trial

data("alzheimers")

Format

A data frame with 480 observations on the following 4 variables.

trt: Treatment factor: Low, High, Placebo
patient: Patient id number
month: Month number: 2,4,6,8,10,12
score: Score for disease

Details

Patents had two daily doses of placebo, low dose, or high dose of a treatment for Alzheimer's disease.

Patients were assessed every 2 months for 1 year.

Disease progression was measured with the Alzheimer's Disease Assessment Scale, which evaluates memory, language, and praxis function. Scores range from 0 to 70, with higher scores indicating greater severity of disease.

Key question: Do the treatments have different response profiles over time?

Source

Glenn Walker and Jack Shostack. 2010. Common statistical methods for clinical research with SAS examples. SAS publishing.

References

None.

Examples

data(alzheimers)
require("lattice")
#> Loading required package: lattice
xyplot(score ~ month|trt , data=alzheimers, groups=patient,
       xlab="month", ylab="ADAS cognitive score", type='l',layout=c(3,1),
       scales=list(x=list(rot=90, cex=.75, alternating=FALSE)))