The other criticalitem here is to involve customers in their natural environment, where they consume your service or use your product (not depending on focus groups, which are artificial and subject to affect contagion) into your development process as early as possible.
Thus we get the ins and outs of what particular promotions might do to that critical number, the year-over-year of same-store sales, or whether a new menu item such as hot breakfasts might induce patrons to spend even more.