Question

A study was done to evaluate the possible effects of food on mood. Twenty college students were randomly assigned to either Condition 1 (an all-carbohydrate lunch) or Condition 2 (an all-protein lunch). One hour after eating lunch, each participant rated his or her degree of sleepiness, with higher scores indicating higher degrees of sleepiness. The researchers wanted to determine if the degree of perceived sleepiness differed as a function of the assigned food group. What would be the null and alternative hypotheses for this test? Would the alternative hypothesis be one-tailed (directional) or two-tailed (non-directional)? Why? What would be the appropriate analysis to use to test these hypotheses? Explain!

Answer 1

Hypothesis:

Average score of sleepiness for carbohydrate lunch and protein lunch is same.

Average score of sleepiness for carbohydrate lunch and protein lunch is different.

Alternative hypothesis is two tailed (non-directional). Because researchers wanted to determine if the degree of perceived sleepiness differed as a function of the assigned food group.

We use independent sample t test for testing this hypothesis, because samples are independent. And we don't know population standard deviation.