Homework

Question 9

A clinical psychologist is studying the efficacy of a new drug medication for depression. The study includes a placebo group (no medication) versus a treatment group (new medication). He then measures the differences in depressive symptoms across the two groups.

What would a Type I error represent within the context of his study? How can he reduce the risk of committing a Type I error? How does this decision affect the risk of committing a Type II error?

Within the context of this study a type I error would be

[Answer here in complete sentences]

Section 3: Case Studies of Hypothesis Testing

Question 10

You are running a series of statistical tests in SPSS using the “standard” criterion for rejecting a null hypothesis. You obtain the following p values.

            Test #1 calculates group differences with a p value = .07.

            Test #2 calculates the strength of association between two variables with a p value = .50.

            Test #3 calculates group differences with a p value = .001.

For each Test below, state whether or not you reject the null hypothesis. For each test, also explain what your decision implies in terms of group differences (Test 1 and Test 3) and in terms of the strength of association between two variables (Test 2).

Test #1 (group differences) =

Test #2 (strength of association) =

Test #3 (group differences) =

Question 11

A researcher calculates a statistical test and obtains a p value of .86. He decides to reject the null hypothesis. Is this decision correct, or has he committed a Type I or Type II error? Explain your answer.

[Answer here in complete sentences]

Question 12

You are proposing a research study that you would like to conduct while attending Capella University. During the proposal, a committee member asks you to explain in your own words what you meant by saying “p less than (<) .05.” Provide an explanation.

[Answer here in complete sentences]