8.11. Refer to Brand preference Problem 6.5. a. Fit regression model (8.22). b. Test whether or not the interaction term can be dropped from the model; use = .05. State the alternatives, decision rule, and conclusion. 6.5. Brand preference. In a small-scale experimental study of the relation between degree of brand liking (Y) and moisture content (X) and sweetness (X) of the product, the following results were obtained from the experiment based on a completely randomized design (data are coded): i: X: X2: Y: 1 4 2 64 2 4 4 73 3 4 2 61 14 10 4 95 15 10 2 94 16 10 4 100