1. For each of the following research scenarios, indicate: i. Which type of t-test (one-sample, independent, dependent) is appropriate for research scenario described; and ii. What characteristic(s) of the research scenario described you used to make your choice

a. Dr. Lofgren was interested in the effects of stress on ability to concentrate. He had 40 participants complete two counterbalanced conditions: a control condition where they spent time in the lab but didn't experience stress induction, and an experimental condition where they completed a lab-based stress task to induce stress. After experiencing each condition, the participants then completed a task requiring deep concentration to complete; the time it took to complete the task was recorded, with quicker completion times reflecting better ability to concentrate. Dr. Lofgren hypothesized that experiencing high stress would lead to poorer ability to concentrate (i.e., slower completion times). (1 mark)

b. Researchers were interested in the effect of a new drug therapy on manic symptoms in patients diagnosed with bipolar disorder. 50 participants diagnosed with bipolar disorder spent 6 weeks with no drug treatment, after which their self-reported manic symptoms were measured. Another group of 50 participants diagnosed with bipolar symptoms spent 6 weeks taking a new drug treatment, after which their self-reported manic symptoms were measured. The two groups' mean self-reported manic symptoms were then compared. The researchers predicted that manic symptoms would be lower in the drug treatment group than in the no treatment group. (1 mark)

c. A professor at York University is interested in whether York psychology students perform as well as in their stats courses as psych students from other universities across Ontario. The average grade for second year stats courses at York from the past 10 years is 77% with a standard deviation of 15%. The professor compared this data to the average for psychology stats courses across all Ontario universities from the same time period, 75%. (1 mark)