5.3.3 Quantitative - schematic and mathematical approaches
The quantitative approach to decision making is derived from the concept of project management that allocates mathematical weightings for managing problems associated with time, work allocation, costs and co-ordination of a project. Three illustrative techniques are Decision Trees, PERT and CPM. All approaches are also major techniques used in risk analysis and quantification of risk. Making good decisions demands a thorough analysis of all key issues, with information formulation and input throughout.
Decision Trees are a schematic representation of the alternatives available and their possible consequences. PERT (Program Evaluation and Review Technique) was designed in the late 1950s to help coordinate the US Polaris Weapon System program that involved more than 3,000 separate contractors. CPM (Critical Path Method) was devised by US Dupont to manage a large industrial project also in the 1950s. Both models are similar although CPM is simpler than PERT. Essentially, CPM allocates a critical path of activities to where decision making is sequenced to ensure problems are resolved. Decisions are made in a logical sequence that link ultimately to provide key points of reference, and even time frames to accomplish activities. PERT also weights optimistic, probable and pessimistic scenarios along the path. Because of its use of probabilities, PERT is used in problem solving where there is little precedence for a solution strategy. CPM is used where there is considerable past experience with similar problems and so the solution is one of strategic planning rather than exploration.
Both PERT and CPM are management tools and therefore are only as good as the managers who implement them and the people who make input. PERT and CPM are expensive to implement and so various qualitative adaptations have been made. Software packages for project management are available of both PERT and CPM and the computer application of qualitative approaches to problem solving offers managers a strategic approach to problem solving. The sections on PERT and CPM should be reviewed with reference to the use of these tools to measure risk when decisions are made in an environment of uncertainty.