This data set comes from Section 52.3.

Average reaction times before and after alcohol (centimetres)

Caffeine,Before,After
Yes,11.83,18.30
Yes,11.16,17.80
Yes,11.94,19.00
Yes,12.04,19.01
Yes,12.14,19.20
Yes,12.61,18.70
Yes,12.07,18.55
Yes,12.16,18.20
No,12.02,19.79
No,11.14,17.40
No,11.10,17.90
No,11.89,16.60
No,12.09,17.50
No,11.93,19.00
No,12.16,18.60
No,12.64,20.00