Few rigorous academic studies have yet been published documenting the moderating effect of tiers of customers on profits. While both Reichheld (1996a, 1996b) and Blattberg and Deighton (1996) have offered arguments, heuristics, and methodologies for determining segment profitability, these methods need to be applied and their results disseminated to affirm these concepts. In one of the few academic studies conducted to demonstrating the importance of focusing on profitability with individual customers, Grant and Schlesinger (1995) estimated the full profit potential across tiers of customers. Using a Canadian grocery store context, they calculated the impact of expanding the customer base by 2 percent with primary shoppers: a profitability increase of more than 45 percent.