Page 1 of 4 ID# Exam 2 PS 217, Spring 2008 As always, the Skidmore Honor Code is in effect. At the end of the exam, I have a sheet on which you will attest to your adherence to the Honor Code. Read each question carefully and answer completely, showing all your work. Good Luck! 1. (From G&W7) People with agoraphobia are so filled with anxiety about being in public places that they seldom leave their homes. Knowing this is a difficult disorder to treat, a researcher tries a long-term treatment. A sample of individuals report how often they have ventured out of the house in the past month. Then they receive relaxation training and are introduced to trips away from the house at gradually increasing durations. After two months of treatment, participants report the number of trips out of the house they made in the last 30 days. Analyze the data below as completely as possible [15 pts] Participant Before Treatment After Treatment 1 0 4 2 0 0 3 3 14 4 3 23 5 2 9 6 0 8 7 0 6 Sum (T) 8 64 ΣX2 22 922 SS 12.86 336.86Page 2 of 4 2. (From G&W1) A scientist tests two drugs for their effects on insomnia. A sample of n = 10 insomniacs is pre-tested with a placebo before bedtime, and the latency to sleep is measured to serve as a baseline. A week later, the subjects receive Drug 1 before bedtime, and the time that lapses between drug administration and sleep onset is measured again. Finally, a week later Drug 2 is tested in the same fashion. The latency to sleep (in minutes) is the DV in the analysis seen below. Complete the source table and interpret the results of this study as completely as you can. [15 pts]Page 3 of 4 3a. (From G&W1) Does coffee help people to become sober more quickly after drinking too much? The (made-up) data below represent the results from an experiment intended to address this question. A sample of 40 volunteers is randomly divided into four groups. One group serves as a control and receives no alcohol. Subjects in each of the remaining three groups drink a fixed amount of alcohol in a one-hour period. During the next half hour, subjects in the second group drink two cups of decaffeinated coffee, subjects in the third group drink two cups of regular coffee, and subjects in the final group drink two cups of water. Finally, all subjects are given a reaction time test to determine mental alertness (i.e., faster reaction times indicate greater alertness). Complete the source table below and interpret the results of this study as completely as you can. [15 pts]Page 4 of 4 3b. Suppose that you had only the Descriptive Statistics for the analysis above. How could you use that information to determine the MSWithin Groups? [2 pts] 3c. What parameter is estimated by MSWithin Groups? [2 pts] 3d. Again, look at the Descriptive Statistics for the analysis above. What information found in that table is driving the MSBetween Groups? [2 pts] 3e. Let’s presume that regular coffee would actually speed up reaction times, but that its effect was quite small. How could you detect the effect of regular coffee in an experiment? [2 pts] 3f. Suppose that this experiment were to be conducted as a repeated measures design. In other words, the 40 scores came from n = 10 people who were each tested under each of the four conditions. What would happen to your dfError? What would likely happen to your F-ratio? [2
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