In the previous chapter we saw a two-factor experiment to test how microwave power and temperature affect popping. She chooses 3 levels of Power (low, medium, and high) and 3 Times (3 minute 4 minutes, and 5 minutes), running one bag at each condition. She counts the number of uncooked kernels as response variable.
a) What are the null and alternative hypotheses for main effects?
b) How many degrees of freedom does each factor s of squares have? How about the error sum of sq
c) Should she consider fitting an interaction term to model? Why or why not?