This paper describes the work of Consumers' Association, publishers of Which?, and of The Survey Unit, giving some details of their aims, organisation, and methods, and describing briefly the problems, particularly those associated with data collection, storage and publication, which they face. The second section of the paper describes in detail the Which? Monitoring Team, a large-scale postal panel study which obtains information from nearly 13,000 informants on the reliability and repair records of a range of consumer durables: the transfer of the data and administration of this panel to an interactive database system is also described. The paper then goes on to examine the problems of obtaining, storing and updating the quantities of data needed for publication in a magazine such as Which?. Finally, the paper briefly considers the question of publication and discusses a number of ways in which the dissemination of data for the consumer may change in future.