A tool for integrating time, cost and quality perspectives in Probability Impact (P-I) Tables

Abstract

One widely documented tool for project risk analysis is the Probability-Impact (P-I) Table, which assesses the probability of occurrence of a risky event and its likely impact on the project objectives, which are typically articulated in terms of cost, time and quality. Whilst there are numerous adaptations of the P-I Table, they are all consistent in treating the project objectives as independent and unrelated variables. This is a major limitation of the tool and reduces the P-I Table’s practical applicability, as in most project contexts the probabilities and impacts of a risky event on the project objectives will be inter-related. To address this limitation, this paper presents a new tool that uses vector theory to enable a single calculation of the overall probability and impact, incorporating the perspective of all three objectives. The tool is illustrated through a practical application to a real case construction project.