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” patternb. The expectation before doing the study was that estrogens cause endometrial cancer of the uterusc. The pattern of association could be expressed by a straight-line functiond. Type II error was the most important potential error to avoide. Only one control group was being used
B – The expectation before doing the study was that estrogens cause endometrial cancer of the uterus
The underlying assumption justifying a one-sided rather than a two-sided test in many studies examining the association between estrogens and endometrial cancer of the uterus is that the expectation before doing the study was that estrogens cause endometrial cancer of the uterus (Option b).
A one-sided test is used when a study is designed to test a specific direction of an association or difference between groups. In this case, the researchers expected that estrogens would increase the risk of endometrial cancer, and they wanted to test this specific direction. The null hypothesis would be that there is no association between estrogens and endometrial cancer, and the alternative hypothesis would be that estrogens increase the risk of endometrial cancer.
Therefore, a one-sided test is appropriate because it allows the researchers to test only the direction of interest, which is the potential harmful effect of estrogens on endometrial cancer. A two-sided test, on the other hand, would test for any association, regardless of the direction, which is not as relevant in this case.
Therefore, the most appropriate answer is b. The expectation before doing the study was that estrogens cause endometrial cancer of the uterus.