Outlines several specific recommendations that would assist in the implementation of the Public Utility Regulatory Policy Act of 1978 (PURPA). Suggestions emphasize the collection of marginal cost data. Measures of short and long run marginal costs assist in the implementation of several sections of PURPA as well as other ratemaking activities. In view of the costs of collecting, storing, and disseminating large amounts of data, the authors recommend only demonstratively useful data be collected. Further, the Federal Energy Regulatory Commission should consider sampling techniques in order that unnecessary costs are not imposed on utilities.