Intertemporal Indicator Evaluation: A Preliminary Note on Problems for Evaluating Time Stream Data for Environmental Policy Analysis

Abstract

Assumptions regarding the aggregation of time stream data (e.g. "discounting") are crucial in the evaluation of regional development proposals and the assessment of environmental impacts. Nonetheless, present practice reflects a great deal of confusion, ambiguity, caprice, and downright error in the calculation and implementation of such assumptions. We present in this paper the outlines of an approach to inter-temporal indicator evaluation for use in the analysis of regional development alternatives. Our ultimate objective is pragmatic: We wish to develop a practical framework for the reduction and comparison of time stream data for evaluation of public programs and policies. As a foundation for this approach, however, it has been necessary critically to review the existing controversy on intertemporal aggregation in a public policy context, and to clarify the practical implications of the, points at issue. Three interrelated themes pervade this review and provide a conceptual focus for the work.