Event Chain Methodology

vent chain methodology (ECM) views tasks as state changes which occur at particular instant. A traditional task is viewed as period of time during which a state change event (from 'ground' to 'completed' is likely to happen (less likely at the start of the period; more likely at the end)

Events are linked in that the occurrence of one event can effect the timing or nature of other events in the project. In the context of traditional tasks this an event link takes the place of a dependency.

A key feature of this analysis is that risks (and opportunities) can also be modelled as this kind of 'event'. In this way links can be made between tasks, risks and opportunities in a single model.

This method is very heavy on computation and upfront analysis it is only suitable where this is practical. The network of events can only be analysed using some additional risk modelling strategy such as Monte Carlo.

Method

1. Create a schedule using best-case estimates. This may seem optimistic but the method deals with optimism via risk rather than duration buffers. For each task assign a probability curve for the completion event starting from 0 percent that start of the tasks duration to some higher (non 100% value) at the end. You can assign probability of 50% at the best case estimated duration then use some heuristic to extend the curve beyond that time.

2. Create a risk break down structure and assign them probability curves also.

3. Create links between events of all types.

4. Perform a quantitative analysis using Monte Carlo simulations.

5. Perform a sensitivity analysis as part of the quantitative analysis. Sensitivity analysis helps identify the crucial activities and critical events and event chains.

6. During the project alter the event networks and analysis to reflect reality and fresh assessments.