Greetings Class,

Here are the questions for the Chapter 09 Activity.

1. Under what circumstances is a t statistic used instead of a z-score for a hypothesis test?

2. Justin wants to know whether a commonly prescribed drug does improve the attention span of students with attention deficit disorder (ADD). He knows that the mean attention span for students with ADD who are not taking the drug is 2.3 minutes long. His sample of 12 students taking the drug yielded a mean of 4.6 minutes. Justin can find no information regarding _x , so he calculated s²_x=1.96.

a. Identify the independent and dependent variables.

b. In a sentence, state the null hypothesis being tested.

c. Using symbols, state the null and alternative hypotheses.

d. Determine the critical region using a one-tailed test with alpha = .05.

e .Conduct the hypothesis test (Do the math and compare the t-critical and t-obtained values).

f. State your conclusions in terms of H₀ (Should you reject the H₀ or fail to reject/accept the H₀).

g. Based on your analysis, is there a relationship between the drug and attention span?

3. On a standardized spatial skills task, normative data reveal that people typically get = 15 correct solutions. A psychologist test n = 7 individuals who have brain injuries in the right cerebral hemisphere. The number of correct solutions for these individuals yielded a sample mean of 11 correct solutions and a sample standard deviation of 2.5. Determine whether or not right-hemisphere damage results in significantly reduced performance on the spatial skills task. Test with alpha = .05 and a one-tailed distribution.

a. Identify the independent and dependent variables.

b. In a sentence, state the null hypothesis being tested.

c. Using symbols, state the null and alternative hypotheses.

d. Determine the critical region using a one-tailed test with alpha = .05.

e. Conduct the hypothesis test (Do the math and compare the t-critical and t-obtained values).

f. State your conclusions in terms of H₀ (Should you reject the H₀ or fail to reject/accept the H₀).

g. Based on your analysis, is there a relationship between the drug and attention span?