Testing the Exogeneity Specification Underlying the Monetary Approach to the Balance of Payments
用Geweke方法检验国际收支货币分析法中关键变量的外生性假设，发现样本国家（澳大利亚、法国、德国、挪威、瑞典）的假设均被拒绝，质疑该模型的理论有效性和实证证据的准确性。
D ESPITE acute interest in Monetary Approach to Balance of Payments (MBOP) over past several years, both as an explanation of worldwide inflationary epidemic of late 1960s and early '70s (Johnson, 1972b) and as a simple and manageable theoretical basis for policy recommendations by groups like IMF (Rhomberg and Heller, 1977), no general consensus has been reached as to validity of monetary model. One reason for this is that task of interpreting results of plethora of empirical tests of monetary approach' has been complicated by controversy over accuracy of exogeneity assumptions underlying MBOP that are implicit in those studies. These include exogeneity with respect to reserve flows of determinants of demand for nominal money balances-the domestic price level, interest rate and level of real income-as well as domestic credit component of a country's money supply. Exogeneity makes task of interpretation difficult, for if MBOP assumptions regarding exogeneity are incorrect, then, to borrow Geweke's (1978, p. 163) words (and to add studies in MBOP literature to which they would apply), the otherwise identifying restrictions imposed on structural equations may not be sufficient to identify those equations (Argy and Kouri, 1974; Genberg, 1976), estimation procedures will be inconsistent (e.g., Bean, 1976; Zecher, 1976), and model cannot adequately portray dynamics of system it seeks to describe. This last problem transcends any issue of estimation (although it is not unrelated) for it implies that theoretical specification of MBOP is incorrect to begin with, thus invalidating putative reduced forms of MBOP that have come to represent approach and form basis for policy recommendations alluded to earlier. Historically, exogeneity was simply assumed as something not amenable to testing. Recently, however, Geweke (1978) has demonstrated that specification of exogeneity is a hypothesis with testable implications. The purpose of this paper is to test formally exogeneity hypothesis underlying empirical tests of MBOP specifically, and theoretical specification of model in general, using Geweke's methods. It is found that hypothesis that variables mentioned above are in fact exogenous can be rejected for each and every country in sample. This finding casts some doubt on theoretical validity of MBOP and even more doubt on accuracy of much of empirical evidence garnered in its support. The plan of paper is as follows. In section II a MBOP model is briefly presented and its exogeneity restrictions are highlighted. In section III formal test of exogeneity is discussed, and then in section IV results of tests using data from Australia, France, Germany, Norway and Sweden are presented. Section V contains some conclusions.