A chain of bookstores wants to develop multiple regression models of sales for two purposes. First, they want to be able to evaluate potential locations for new stores, and, second, they want to establish norms that can be used to evaluate the performance of store managers (i. e., they want to be able to predict the sales of an "average" store, so they can judge the input of each manager). *Note this is essentially proposing theories of what makes a location attractive and what makes a store successful--what factors "cause" a location to be good, and what factors "cause" store managers to be profitable