Abstract
In designing management information systems (M.I.S.), organizations tend to concentrate on computer-related issues, whereas research in M.I.S. has a behavioural tradition. This paper reports on the design and implementation of an M.I.S. for a bank, in which the key issues were to do with neither computers nor behaviour. The key issues concerned decisions and data. It was found to be important to analyse the decision-making system, to adopt an evolutionary approach to design, to reduce the data to manageable proportions, to format the data and to refine the data by use of techniques of management science.