Dr. Smith conducted an experiment to study the effects of massed versus distributed practice on memory. Twelve participants were randomly assigned to study a short chapter of a history text during either a single 3-hour session or 3 one-hour sessions separated by 24 hours. Twenty-four hours after the study session(s) ended, the participants took an examination on the information in the chapter and the number of correct answers was recorded. Data from that experiment are shown below.

Massed Practice	Distributed Practice
55	74
67	67
55	87
47	77
59	68
70	75
X1 = 58.83	X2 = 74.67
S1 = 8.50	S2 = 7.23