Description data set vitamin:

Vitamin is a simulated dataset in groupedData format. 
It contains the well beeing of 50 children who were brought to the doctors on the first day after they caught a cold.
Some were given a vitamin preparation and others were given a candy. The treatment and the placebo groups are randomized.
For each child, the well being was measured 30 times over time. The first measurement takes place BEFORE the vitamin/placebo is given.


The data set contains the following variables:

y: a numeric response vector giving the well being of the child.
group: a dummy coded variable for the randomized treatment, either a vitamin preparation is given (group=1) or not (group=0)
time: a numeric vector giving the number of the measurement for each child. The first measurement takes place BEFORE the vitamin/placebo is given.
child: an ordered factor identifying the child whose health score is measured.