Final answer:
Both one-tailed and two-tailed hypotheses can be used with ANOVA in Stata, depending on the specific research question and the hypothesis being tested.
Step-by-step explanation:
In the context of hypothesis testing with analysis of variance (ANOVA) in Stata, it is not true that only a one-tailed hypothesis should be used. Both one-tailed and two-tailed hypotheses can be used with ANOVA in Stata, depending on the specific research question and the hypothesis being tested.
For example, if the research question is whether there is a difference in means between two groups, a two-tailed hypothesis test can be used. On the other hand, if the research question is whether one group has a higher mean than another, a one-tailed hypothesis test can be used. It ultimately depends on the specific hypothesis and the directionality of the research question.