In many studies examining the association between estrogens and endometrial cancer of the uterus, a one-sided significance test was used. The underlying assumption justifying a one-sided rather than a two-sided test is:
a. The distribution of the proportion exposed followed a "normal" pattern
b. The expectation before doing the study was that estrogens cause endometrial cancer of the uterus
c. The pattern of association could be expressed by a straight-line function
d. Type II error was the most important potential error to avoid
e. Only one control group was being used
Answer: b. The expectation before doing the study was that estrogens cause endometrial cancer of the uterus