Does Economic Theory Play a Role in Regulatory Decisions? The CRTC Cost Inquiry
研究了加拿大广播电视电信委员会（CRTC）在电信成本调查中如何受经济学家证词影响，分析了增量成本法和完全分配成本法两种方法的取舍。
Since economists are often required to testify at regulatory hearings, it is pertinent to inquire as to the extent that their testimony influences the regulatory commission in its decision. Since commissions regularly evaluate the various arguments in the text of their decision, it is certainly possible to ascertain to what extent a commission was influenced by a particular testimony. This paper considers one particular case in detail-the Canadian Radio-television and Telecommunications Commission (CRTC) Phase III cost inquiry for federally regulated telecommunication carriers. The purpose of the paper is to ascertain what motivated this commission in its decision. These hearings provide a particularly good case study, since the intent of the CRTC was to evaluate a number of costing methodologies and, on the basis of the evidence, to select an appropriate methodology; thus a considerable part of the evidence related to economic theory. When a regulatory commission addresses the problem of determining the rate structure for a multiproduct firm, it necessitates establishing the underlying structure of the firm's costs as one of the bases upon which rates might be set. As such, an increasing number of regulatory authorities at both the state and federal levels in the United States, as well as in Canada, have initiated generic proceedings for the purpose of establishing a standard methodology by which such costs will be determined-in particular in the fields of energy, trucking, and communications. The fact that such inquiries have continued for over thirty years, with no commonly agreed upon methodology, suggests that costing is a much more difficult concept than would be expected. The problems that confront the regulator include the determination of the appropriate time horizon, the decision as to the appropr ate level of disaggregation of products and/ o services, the decision as to how shared costs are to be allocated, the methods to be used for dealing with both economies of scale and cost complementarities, the question as to the choice of embedded or current cost, and the choice of methodology to be used. Faced with such issues, it is not surprising that counsel will appeal to the expertise of economists t support (or refute) a particular argument. In most situations, there is a trade-off between what one would like to do, and what is possible; costing is no exception. Two broad costing methodologies emerge-incremental costing (IC), and fully distributed costing (FDC).' These two methodologies differ in two fundamental ways. First, FDC costs are usually (though not necessarily always) based on historical, accounting costs, while incre-