1. A method of grouping one or more retail store units of a first set of retail store units together based on common economics comprising: a) generating at least one fixed price index for each retail store unit over a select period of time; b) identifying a number of variables associated with each retail store unit, each variable having a standardized value; c) regressing profits against the price index and the product of the price index and the variables, using a computer, and generating a regression coefficient for each variable; and d) identifying which variables have more significant regression coefficients, and grouping retail store units having these variables together as being in a common economic market using the computer.