I. Introduction
II. Model, data, and methods
III. Results

『IV. Conclusions
　Recent legislation, the National Commission on Supplies and Shortages Act of 1974, together with other policy making has increased interest in the role of natural resources for our economy and the adequacy of their supplies in the future. The results of this analysis of a naive model of the change in relative prices of selected natural resource commodity aggregates, which formed the basis of judgments on materials policy in the past, suggest that broad conclusions, having potentially significant impacts that are based on these data alone, would seem unwise. These conclusions are consistent with consideration of the inherent difficulties associated with interpreting the series themselves. The composition of the aggregates and the nature of the U.S. economy has changed significantly over the period 1900 to 1973, so that evaluations of resource scarcity without detailed analysis of the character of the markets for the specific commodities within each aggregate, as well as the institutional changes during the period, do not seem possible.』

References