These data were drawn from a study concerning the training of severely retarded persons to follow instructions during a play activity; see Kazdin and Erickson (1975). During the playtime, a resident was instructed to complete a sequence of behaviors related to playing ball. This was the A phase. During the B phase, a resident not only received instruction but also food reinforcement and assistance from a staff member. The data are given in the columns below (Phase is 1, Phase B is 2):

  y    phase time
 0.0     1    1
 0.3     1    2
 0.2     1    3
 0.1     1    4
 0.3     1    5
 0.3     1    6
 0.3     1    7
 0.6     1    8
 0.5     1    9
 0.4     1   10
 0.1     1   11
 1.6     1   12
 1.5     1   13
 1.4     1   14
 1.6     1   15
 1.5     1   16
 0.8     1   17
 2.5     2   18
 2.6     2   19
 2.5     2   20
 2.4     2   21
 2.5     2   22
 1.6     2   23
 1.7     2   24
 2.5     2   25
 2.6     2   26