We would like to build a quantitative model to explain the variation in quarterly revenue. A reasonable model is as follows:

Predicted Sales  abQuarter#cQ1dQ2eQ3 where

a, b,

c, d, and e are parameters to estimate.

a. Find the values of

a, b,

c, d, and e that best fit this model.

b. What does your model say about the trend and seasonal aspects of Nike sales? (Hint: The trend effect is captured by the term involving Quarter #.

Seasonal effects may be interpreted relative to the quarter, Q4, that we have omitted from the analysis.)