Question: A famous paper on the effects of marijuana smoking ("Clinical and Psychological Effects of Marijuana in Man'" Science (1968):1234-41) described the results of an experiment in which the change of heartbeat rate was measured for nine subjects who had never used marijuana before. Measurements were taken both before and 15 minutes after smoking marijuana at a low-dose level and before and 15 minutes after smoking a placebo (untreated) cigarette. Do the data suggest that marijuana smoking leads to greater increase in heartbeat rate than does smoking a placebo cigarette? Test at the .05 level.

Here are the increases, in beats per minute:

Subject	Placebo	Marijuana
1	16	20
2	12	2
3	8	8
4	20	8
5	8	4
6	10	20
7	-8	20
8	6	11
9	8	20