A researcher, investigating factors affecting summer attendance at privately operated

beaches on Lake Ontario, collected information on attendance and 12 explanatory vari-

ables for 40 beaches. Two summers were studied, of relatively hot and relatively cool

weather, respectively. A variable selection algorithm is to be used to reduce the number

of explanatory variables for the final regression model. Should the variables reduction

be done for both summers combined, or should it be done separately for each summer?

Explain the problems involved and how you might handle them.