Continuing from the data in Problem 11.11, the research group selects another random sample for observation. This time the participants had to record if they had coffee, tea, or neither two hours before they went to sleep and their mood upon waking the next morning. The file Sleep2 contains this data along with each participant's sleep duration.

At the 0.05 level of significance,

a. is there an interaction between beverage and mood?

b. is there an effect due to beverage?

c. is there an effect due to mood?

d. Plot the mean delay for each beverage for both moods.

e. What can you conclude about the effect of beverage and mood on mean sleep duration?

Problem 11.11

A group of researchers is analyzing the effects of consuming caffeine (coffee or tea) before going to bed on sleep duration. Three groups of 25 people each were selected. In the first group, all participants consumed coffee within two hours before going to bed. In the second group, all participations consumed tea within two hours before going to bed, and participants from the third group were given no coffee or tea in the two hours before they went to bed. The file Sleep contains the sleep duration of each participant in minutes.