Towards realism in network simulation

The use of networks handling uncertainty to provide a temporal risk analysis of projects is now widespread. However, such analyses frequently give rise to very wide probability distributions, and thus in practice are described as not credible. This is largely because the simulations do not reflect the actions that management would take to bring late-running projects under control. These are difficult to include in models, not because the actions themselves are complex, but rather because the effects of those actions are not well-understood. These effects are often much less effective than expected and some are counter-intuitive. However, much work has been done in modelling projects using system dynamics, and this work can give some useful insights into the effects of management actions in projects, both their behaviour and indications of their cumulative impact. This paper has attempted to describe these indications and then to apply such lessons to network simulations, to gain the benefit of the insights without losing the operational advantages of the networks. Some small illustrative models of the effects are given. It is hoped that the use of such modelling can help to bring additional realism to probabilistic network modelling.