Identifying "Best-Buys" In The Market Of Prepaid Mobile Telephony: An Application Of Imprecise Dea

Value-for-money is a widely used criterion to locate “best-buys” in a market of competitive products or services. The term “value” represents a composite measure of what a consumer gets from a product or service, while the term “money” is what the consumer pays for it. In the absence of individual preferences, the problem of identifying best-buys by the value-for-money criterion can be formulated as an imprecise DEA model with a single input (price) and multiple outputs (indices and performance estimates). In accordance with the DEA terminology, efficient units (products or services) are those that worth their price. As the price of a particular product can vary from dealer to dealer or due to different discount policies, it is usually known to lie within a bounded interval, between the lowest and the highest price recorded in the market. On the other hand, product outputs may be measured either by exact values or bounded intervals (overall evaluation judgments made by different experts, for example) or ordinal variables (product ratings obtained by experts or surveys). In this paper we use the imprecise DEA model to classify prepaid mobile telephony packages in the Greek market by the valuefor-money criterion.