Creative Confectioners is planning to introduce a new brownie. A small-scale “taste test” was conducted to assess consumers’ preferences (Y) with regard to moisture content (X1) and sweetness (X2). Data from the taste test may be found in the file Dat9-15.xls on your data disk.

a. Prepare a scatter plot of moisture content versus preference. What type of relationship does your plot suggest?

b. Prepare a scatter plot of sweetness versus preference. What type of relationship does your plot suggest?

c. Estimate the parameters for the following regression function:

Ŷi = b0 + b1X1i + b2X12i + b3X2i + b4X22i

What is the estimated regression function?

d. Using the estimated regression function in part c, what is the expected preference rating of a brownie recipe with a moisture content of 7 and a sweetness rating of 9.5?