Do external rewards—things like money, praise, fame, and grades promote creativity? Researcher Teresa Amabile suspected that the answer is no, and that internal motivation enhances creativity. To find out, she recruited 47 experienced creative writers who were college students and divided them at random into two groups. The students in one group were given a list of statements about extrinsic reasons (E) for writing, such as public recognition, making money, or pleasing their parents. Students in the other group were given a list of statements about intrinsic reasons (I) for writing, such as expressing yourself and enjoying playing with words. Both groups were then instructed to write a poem about laughter. Each student’s poem was rated separately by 12 different poets using a creativity scale. These ratings were averaged to obtain an overall creativity score for each poem. The table shows summary statistics for the two groups.

We used software to randomly reassign the 47 subjects to the two groups 100 times, assuming the treatment received doesn’t affect each individual’s creativity rating. A dotplot of the simulated difference  in mean creativity rating is shown.

a. Why did researchers randomly assign the subjects to the two treatment groups?

b. Estimate and interpret the P-value.

c. What conclusion would you make?

d. Based on your conclusion in part (c), could you have made a Type I error or a Type II error? Justify your answer.

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Group name Mean SD Intrinsic 24 19.883 4.44 Extrinsic 23 15.739 5.253