1. Consider the model Pt = β0 + β1 St + ut, where P and S are profits and sales of a company at time t. The company’s sales manager believes that this relationship is different across the fall, winter

1. Consider the model Pt = β0 + β1 St + ut, where P and S are profits and sales of a company at time t. The company’s sales manager believes that this relationship is different across the fall, winter, spring and summer seasons. She gives you data for each season for 20 years (n = 80) and wants you to test the null hypothesis that there is no difference in the parameters across the seasons.