Psychology 201--Research/Statistics Worksheet

Dr. Lanthier

A. Dr. Darley predicts that people in a hurry will be less helpful to strangers than people not in a hurry. He randomly assigns his 30 volunteer subjects into two groups. Participants in group 1 are told that they have to give a talk in the next building but that they are already 15 minutes late. Participants in group 2 are told that they have to give a talk in the next building but it starts in 30 minutes. Dr. Darley arranges to have an actor lying on the sidewalk between the two buildings. The actor poses as an injured person, moaning and groaning that he is hurt. Dr. Darley measures how many of his volunteers stop to help the "injured person." He found that 4 people in group 1 helped and 13 people in group 2 did. This difference was significant.

Questions:

1. What are the treatment and control conditions in this experiment?

2. What is the independent variable?

3. What is the dependent variable?

4. What are the operational definitions of "in a hurry" and "helpful"?

5. Is Dr. Darley able to conclude that being in a hurry causes people to be less helpful? Why or why not?

B. Recent studies have shown a significant negative correlation between a woman's weight and her net worth (salary, assets, etc.).

Questions:

1. Explain what this means.

2. Draw a scatterplot to illustrate your explanation.

3. Can we conclude that being heavy causes women to have lower net worths? Why or why not?

C. Draw scatterplots to show the shape of the following correlations:

.7 -.6 1.3

D. State police registered the following speeds (12 cars) during a brief observation on I-66. What are the mean, median, and mode of this sample of speeds?

50	45	60	55	60	70
55	60	70	50	65	45