Part 1:

1. In a research study, students who do a puzzle in a warm room take significantly more time than those in an a normal temperature room. t(30) = 3.38, p < .01, Cohen's d= .50. Be specific in answering the questions below as though you were explaining to a fellow student.

a. What does p < .01 mean?

b. Is the effect size considered small, medium, or large? How do you know?

Part 2:

2. Go through and label each step of the 4 steps of the hypothesis testing process.

Label each result with its appropriate symbol and show your work step-by step (including the appropriate formulas you use.)

A therapist would like to evaluate the effectiveness of a procedure for treating depression. A sample of n = 16 depressed clients is obtained and each person's level of depression is measured using a standardized questionnaire before they begin the therapy program. Two weeks after therapy, each client's level of depression is measured again. For this sample, the average level of depression dropped by MD = -8.2 points following therapy. The difference scores had a variance of s2 = 144.

a) What is the IV?

b) What is the DV?

c) Which statistical test would you use? Why?

d) Do the sample data indicate a significant change in depression (2-tailed test)? Test with alpha = .05, 2-tailed test. Make sure to do each of the four steps of hypothesis testing:

1) State the hypotheses.

2) Find the critical region. Boundaries

3) Perform the hypothesis test.

4) Make a decision. Are your results statistically significant? Make sure to state what you conclude about the original question about depression that was studied in the first place.

e) Find Cohen's d (if your results were significant).

Fill in the blank:

The mean of the squared deviations is referred to as ________.