Independent samples t-test A researcher wants to assess the damage to memory that is caused by chronic alcoholism. A sample of n = 10 alcoholics is obtained from a hospital treatment ward, and a control group of n = 10 non-drinkers is obtained from the hospital maintenance staff. Each person is given a brief memory test and the researcher is records the memory score for each subject. The data are summarized as follows: Controls M = 57, SS = 410, n=10 Alcoholics M = 43, SS = 400, n=10. We will use = .05

Answer the seven questions below

Question 1: What are the null and alternative hypotheses, respectively? Write out using appropriate statistical notation.

Question 2: What are the degrees of freedom for this experiment? Remember that df =(n1 -1) + (n2 - 1) and that n=10 in each sample.

Question 3: Given the df above, what is the critical value. (Use the table at the end of your book.)

Question 4: What is the pooled variance (s2p)?? Remember that s2p = SS1 + SS2 / df1 + df2 .

Question 5: What is the standard error for the t statistic? Remember that s(M1 - M2) = s2p/n1 + s2p/n2 .

Question 6: What is the value of the t-statistic? Remember that t = M1 - M2/ s(M1 - M2).

Question 7: Should the null hypothesis be accepted or rejected?