A two-factor ANOvA: the null hypotheses, interpretation, and assumptions A fourth-grade teacher suspects that the time he administers a test, and what sort of snack his students ha before the test, affects their performance. To test his theory, he assigns 90 fourth-grade students to one of three groups. One group gets candy (gummy bears) for their 9 AM snack. Another group gets a high-protein snack (a hardboiled egg) for their 9:ss AM snack. The third group does not get a 9:5s AM snack. The teacher also randomly assigns 10 of the students in each snack group to take the test at three different times: 10:00 AM (right after snack), 11:00 AM (an hour after snack), and 12:00 PM (right before lunch suppose that the teacher uses a two-factor, independent-measures ANOVA to analyze these data. Without post hoc tests, which of the following questions can be answered by this analysis?
Check all that apply. Note: Assume that receiving snack is considered one type of snack.)
a. Does the effect of the timing of the test depend on the type of snack the students eat?
b. Does the effect of the type of snack depend on the timing of the test?
c. Is there a difference among the scores for the snack types because a candy snack increases the students' level of happiness, which causes them to exert more effort on the test?
d. Does the type of snack (or lack of snack) affect student performance on the test?