Supermarkets may boast that their prices are lower than their rivals… but who has won out in the battle to convince shoppers? A retailer's performance is subject to a myriad of factors which serve to boost or dampen growth, from overall economic performance to deflationary pressure from rivals and operating cost inflation. But the principal driver behind performance is also the most difficult to measure - customers and their fluid, evolving opinions. These opinions drive customer behaviour, and ultimately sales and profits. As such, the customer is the single most important element of the retail equation. The Index we have devised is the only available system of performance benchmarking which is defined by the customer. It measures how satisfied customers are with the retailers they use, and as such allows you to really understand your customers - and your rivals'. The Consumer Satisfaction Index 2005 sector report: Food & Grocery covers 14 retailers ranging from the big four supermarket groups to hard discounters such as Aldi, Netto and Lidl and smaller national chains such as Iceland and Waitrose.