This data set comes from Section 52.45.

Sleep (hours) for different subjects and caffeine intake

Person,Caffeine,Sleep
A,No,8.0
A,No,8.5
A,No,9.0
A,No,10.0
A,No,9.5
A,No,9.0
A,No,8.0
A,No,10.0
A,No,9.5
A,No,10.0
B,No,9.0
B,No,8.0
B,No,8.0
B,No,9.0
B,No,8.5
B,No,10.0
B,No,8.5
B,No,9.5
B,No,9.0
B,No,10.0
A,Yes,6.0
A,Yes,5.5
A,Yes,6.0
A,Yes,7.0
A,Yes,7.5
A,Yes,5.5
A,Yes,7.0
A,Yes,7.0
A,Yes,7.5
A,Yes,8.0
B,Yes,6.5
B,Yes,6.0
B,Yes,6.0
B,Yes,6.5
B,Yes,7.5
B,Yes,6.0
B,Yes,6.5
B,Yes,7.5
B,Yes,7.0
B,Yes,9.0