Calculate a measure of effect size for the data in Exercise 14.11.

Exercise 14.11

Much has been made of the concept of experimenter bias, which refers to the fact that for even the most conscientious experimenters there seems to be a tendency for the data to come out in the desired direction. Suppose we use students as experimenters. All the experimenters are told that participants will be given caffeine before the experiment, but half the experimenters are told that we expect caffeine to lead to good performance, and half are told that we expect it to lead to poor performance. The dependent variable is the number of simple arithmetic problems the participant can solve in two minutes. The obtained data are as follows:

What would you conclude from these results?

Transcribed Image Text:

Expect good Performance Expect Poor Performance 19 15 14 18 27 22 13 18 15 20 25 22 17 12 21 21 24 14