Do you think it is realistic for Alliance Data Systems (a company who provides transportation processing, credit services and marketing services to clients based in retail, convenience stores, utility companies and transportation companies) to predict the value of the amount of purchase based solely on the amount spent at related stores only? In reality, would you think that there might be other variables that could help explain or predict the amount of purchase? What other consumer-specific variables might be worthy of evaluation in the proposed predictive regression equation? Be specific in your reply.