*20. In Original Source 17, “Monkeys reject unequal pay,” the researchers found that female monkeys were less willing to participate in an exchange of a small token for a piece of cucumber if they noticed that another monkey got a better deal. In one part of the experiment, a condition called “effort control,” the monkey witnessed another monkey being given a grape without having to give up a token

(or anything else) in return. The first monkey was then cued to perform as usual, giving up a small token in return for a piece of cucumber. The proportion of times the monkeys were willing to do so was recorded, and the results are shown in Figure 1 (page 297) of the report. This “effort control” condition was compared with the “equality condition” in which the first monkey was also required to exchange a token for cucumber. For this part of the study, the researchers reported,

“Despite the small number of subjects, the overall exchange tendency varied significantly . . . comparing effort controls with equality tests, P  0.05”

(p 298). (The symbol  means “less than.”)

a. The participants in the study were five capuchin monkeys. To what population do you think the results apply? (Note that there is no right or wrong answer.)

b. The researchers were interested in comparing the proportion of times the monkeys would cooperate by trading the token for the cucumber after observing another monkey doing the same, versus observing another monkey receiving a free grape. The null hypothesis in this test is that the proportion of times monkeys in the population would cooperate after observing either of the two conditions is the same. What is the alternative hypothesis?

c. Based on the quote, what do you know about the p-value?

*d. Based on the quote, what level of significance are the researchers using?

e. What conclusion would be made? Write your conclusion in statistical language and in the context of the example.