Communications to the Editor—A Comment on Location Models

In their recent survey of location models, ReVelle et al. [ReVelle, C., D. Marks, J. Liebman. 1970. An analysis of private and public sector location models. Management Sci.10(11, July) 692–707.] touched briefly on the problem of variations over time in the optimum network of facilities: Are locations set in order to be most efficient with todays population, ten years hence or twenty years hence or an average of all three? This question was left unanswered as it is left unanswered elsewhere in the literature on location studies. However, the question is surely answerable, and the purpose of this note is to describe the approach which has been used by the author in answering this question.