Pschological tests are often used to determine the hostility levels in people. High scores on the HLT pschological test corresponds to high hostility levels. Suppose that 26 college students, all with equally high HLT test scores, were separated into two groups randomly. Group 1 (10 students) was treated for high hostility levels by using Method A; whereas Group 2 (16 students) was treated for high hostility levels by using Method B. Both groups were treated for a period of 5 months, at which time all 26 students were again given the HLT test. Below is the summary data on the HLT test for the two groups.
- Group 1: sample mean is 79 and sample standard deviation is 7
- Group 2: sample mean is 84 and sample standard deviation is 8
- The 95% confidence interval for the difference in the means of the two treatment methods is (-11.4, 1.4). Based in this interval, select the best answer below. Assume that the independent random samples were taken from normal distributions and that the two population variances are equal.
Select one:
A. We are 95% confident that there is no statistically significant difference in the mean treatment methods for hostility.
B. We are 95% confident that Method A is a better treatment for hostility than Method B.
C. We are 95% confident that Method B is a better treatment for hostility than Method A.
D. We are 95% confident that there is a statistically significant difference in the mean treatment methods for hostility.