Researchers wanted to explore the effects of caffeine on sleep in normal, adult women. Twelve women were recruited to participate in the study and they drank a caffeine or no caffeine beverage (they tasted alike) on different days of testing. Participants were give the beverage one hour prior to bedtime at a sleep center, were told to go to sleep at a specified time, and then their sleep latency (the time between closing eyes and the beginning of stage one sleep) was measured using standard sleep recording instruments. The sleep latencies for each woman are recorded below.

Participant	Caffeine	No Caffeine
1	15	7
2	20	11
3	18	14
4	17	5
5	5	7
6	19	6
7	17	10
8	16	12
9	4	3
10	14	9
11	8	5
12	22	12

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1. What is the null hypothesis in this study?
2. What is the alternate hypothesis?
3. What probability should you use and why?
4. What are the degrees of freedom?
5. What is your computed answertvalue?
6. Based on yourtvalue, probability level, degrees of freedom, and critical value, is there a significant difference between the two groups?
7. Interpret your answer--are there differences between the groups? If so, which group performed better?
8. If you have made an error, would it be a Type I or a Type II error? Explain.