Five students were tested before and after taking a class to improve their study habits. They were given articles to read which contained a known number of facts in each story. After the story each student listed as many facts as he/she could recall. The following data was recorded.
before 10 12 14 16 12
after 15 14 17 17 20
Assume there is a real effect. using d, the size of effect for the improvement, equals _________.
A. 0.56
B. 0.52
C. 1.42
D. 1.37
