Do the right thing – when clients aren't clear about what they want

This article draws some methodological and organisational lessons from our experiences in developing and implementing a supply chain model for a multinational company in Brazil. The lessons are from the soft side of OR modelling and centre on factors to which we should have paid more attention: the involvement of all potential users of a model, exploration of how users make decisions in practice and with what data, appreciation of the organisational constraints and culture of the decision-making environment, the pro-active and exhaustive validation of a model with operational users rather than over-reliance on a client executive's strategic view of the model's purpose.