The results of an unpublished Alzheimer's study are reported in Hand 
and Talor (1987). There are two groups of patients, one receiving a 
placebo and one receiving a drug called lecithin. Each patient was 
asked to memorize a list of words. The outcome was number of words
correctly recalled. This "test" was administered at each of five time 
points: 0, 1, 2, 4, and 6 months. There are 48 patients, 22 on drug 
and 26 on placebo. The words used at each testing occasion were 
exactly the same as on previous testing occasions.

It is expected that any treatment effects may be small and slow to
appear because of the nature of dementias. The administration of the
memorization "test" on multiple occasions also introduces a "practice
effect," that is, a subject may improve over time merely because of
carryover effects from one occasion to the next. This may be due to
repeated exposure to the same words and/or repeated exposure to the 
testing situation.

Questions of interest are:

  -- Is there a time trend in recall ability across the five testing
       occasions?  Is it, for example, decreasing?
  -- Does any time trend differ by treatment?

The data set contains treatment in column 1 (0 for placebo and 1 for
lecithin) and test results in columns 2 through 6. There are no other 
covariates available. 

Data source: Hand and Taylor (1987). Multivariate analysis of variance
and repeated measures. London: Chapman and Hall, Inc.