[Once the coefficients of an econometric model have been estimated, the dynamic properties of the resulting system of equations are frequently of interest. In this paper Fourier methods are used to obtain the spectrum matrix of the endogenous variables of the Klein-Goldberger model. The power spectra and coherence and phase relationships implied by the model are derived for selected endogenous variables and are compared with previous results.]

A bstract-This paper uses state space methods to examine the extent to which forecast errors in inventory investment, especially at turning points, may be due to measurement error. It is found that while quarterly observations on both inventory and sales are subject to substantial revision, these revisions have on average only a modest impact on the accuracy of inventory investment forecasts. However, there is evidence that the variance of inventory measurement error increases with the rate of change of inventory stocks. This implies that substantial improvements in forecast accuracy, especially at turning points, are potentially available if the preliminary and revised data are used optimally.

An examination of two types of simple forecasting models using preliminary data compares the merits of optiml versus traditional predictors and indicates the relationship of delay in the availability of data revisions to forecasting accuracy. The Kalman filter approach is used in the first model, based on the optimal use of data containing errors in forecasting. Several suboptimal predictors, which ignore preliminary data, treat it as error-free, or adjust for bias and serial correlation, are then compared. A significant improvement in accuracy is demonstrated with the optimal use of forecasting models. Whether accuracy will improve with more complex models is not yet known. 10 references.

The purpose of this paper is to explore within the context of several simple macroeconomic models the magnitude and significance of the structural changes that have taken place since the 1930's. The method that is used to examine the structural-change hypothesis is first to estimate separately for 1921-41 and 1946-66 the parameters of a macroeconomic model of income determination. The parameter estimates are then compared to see if there are any significant differences between the two periods. Finally, the dynamic properties of the systems for each of the subperiods are derived and compared. The presumption is that the parameter estimates and the implied system behavior will reflect the structural changes that have been effected since the great depression. (Author)

IN order to evaluate alternative stabilization policies, it is necessary to-ascertain the properties of the system into which these are to be introduced. Since this is very difficult in economics, the usual practice is to postulate simple systems which are amenable to analysis by general methods, and then to consider the impact of various stabilization on these systems. Such an approach led Baumol, for example, to conclude that policies automatic or not which appear to be properly designed may very well turn out to aggravate fluctuations [2, p. 21]. This somewhat pessimistic conclusion was suggested by an analysis of the transient response of a deterministic linear system. The question naturally arises whether results similar to those derived by Baumol also hold for stochastic systems. The purpose of this paper is to extend the tools and results derived by Baumol to a linear stochastic system. Since attention will be focussed on the stochastic response of the system, this paper can be viewed as an elaboration of some of the problems discussed by Friedman [5] in connection with stabilization policy. In the next section, some of the properties of stochastic linear systems and linear stabilization are described. Methods which may be used to evaluate alternative stabilization are considered in section III. The paper concludes with several comments on the implications of minimum-variance stabilization policies.

The purpose of a foreign exchange guarantee is not to discourage countries which should devalue from devaluing but to allow monetary authorities to cooperate freely and fully in reducing international monetary instability and to prevent devaluations from taking place which would not take place if adequate cooperative arrangements were available. In this context, it is revealing that the overwhelming majority of agreements concerning international monetary cooperation in the postwar world have contained exchange guarantees.15 Until some radical reforms, are introduced into the international monetary system, the stability of the system will, in large measure, depend on cooperation between the monetary authorities of the leading financial countries. One of the obstacles that has been encountered in this cooperation is the unwillingness of the various monetary authorities to accumulate large amounts of foreign exchange without some sort of exchange guarantee. I do not say the absence of an exchange guarantee is the only obstacle, but it has been, and is, one of the serious obstacles. An exchange guarantee is not a panacea for the world's monetary ills, however, it can make a valuable contribution toward international monetary stability.16