Scenario-robustness methodology: An approach to flexible planning under uncertainty with an application to AIDS-related resource allocation.

摘要

In this thesis the problem of planning under uncertainty is examined. A classification of uncertainty is given with the purpose of identifying those areas where traditional methods for planning under uncertainty fail to prescribe suitable courses of action. Traditional planning methods have increasingly proved inadequate in their handling of the uncertainty inherent in complex and turbulent environments. Methodologies suitable to planning under uncertainty should attempt to preserve future flexibility, by keeping options open for later resolution. This thesis describes the development of Scenario-Robustness Methodology (SRM), a flexible methodology for planning under uncertainty. SRM uses scenario analysis to develop altemative futures, and robustness analysis to determine the most flexible options under those futures, for both the short and long term. A new criterion is proposed for evaluating the consequences of initial decisions in terms both of the positive options which are maintained and of the undesirable options still left open. This criterion is a composite measure which enables decision-makers to give relative weights to positive outcomes (robustness) or negative outcomes (debility), by varying a key parameter. A number of alternative measures of uncertainty which may be employed in a planning situation characterized by a set of initial decisions and a set of altemative future scenarios, are also examined. The coefficient of concordance W is found to be the most useful of such measures. An example is given of the application of SRM to an HIV/AIDS-related resource allocation problem. Planning for HIV/AIDS is selected as a suitable area of application because of the uncertainties surrounding the nature of the disease, the availability of treatments and their timing, and the size of the planned for population. SRM is used to assist in structuring the problem and to identify those initial commitments which are preferable in terms of flexibility. The problem structuring capability of SRM is of particular value since it initiates a process of reflection and negotiation which helps to incorporate in the analysis, in addition to flexibility, other relevant factors which will shape the final selection of an appropriate course of action.