Production depends on the successful co-ordination and management of the physical resources and capital available. Over the decades major effort has been directed at understanding the physical resources, improving the efficiency of production, and developing symbolic models that can be used to explore operational systems. However, a key resource in making use of all the research is the management input. Without an appropriate management input, production is chaotic. Yet little research has been directed at understanding the psychology of decision making, and how the managerial ability of each individual might be improved. The research reporting in this publication is a move towards a better understanding of managerial skill – it involves the development of tests that might be used to assess a manager's ability and approach to decision making. These tests can then be used as a component in training programmes to assess improvements.