Formulated Problem Verification As an Explicit Requirement of Model Credibility

This paper deals with the formulation and formulation verification of a class of problems to which "modeling solutions" are applied. Two main objectives are to develop a procedure for problem formulation and to propose indicators for the formulated problem verification. The class of problems considered is analyzed in two categories as requiring prescriptive or descriptive solutions. A detailed study of each category results in a procedure to guide the analyst during the problem formulation. This procedure is illustrated by a traffic intersection problem. The formulated problem is measured by using indicators to accomplish an evaluation for the formulated problem verification. Indicators are developed to measure: (1) the probability of failing to solve the actual problem, (2) the acceptability of an alternative set of possible outcomes, and (3) how well the formulated problem is structured. An evaluation questionnaire, included in the Appendix, is employed in applying the proposed indicators.