Twenty-five patients (group 1) with chronic lower back pain receive six months of opioid therapy and at the end of the six months have a mean pain level of 15.7 with a sample standard deviation of 4.3. A separate group of 25 patients (group 2) with chronic lower back pain received six months of daily yoga sessions and after six months have a mean pain level of 9.8 with a sample standard deviation of 4.0. We can assume that the population variances in the two groups are equal.
What best fits it?
a. Two-sample z-test
b. Two-sample (pooled variance) t-test
c. Two-sample (unpooled variance) t-test
d. Wilcoxon rank-sum test
e. Paired t-test