NOTE ON HARMONIC MOTION AND THE COBWEB THEOREM*

This note critically examines some recent studies which have rejected the cobweb theorem as an explanation of agricultural production cycles in favour of an alternative model, harmonic motion. It is argued that the only fundamental distinction between the two models lies in the behavivoural decision rule which they assume, and that some of the arguments put forward by proponents of the harmonic motion model are illusory.     

An appraisal of the Box-Jenkins approach to univariate time series analysis

Summary Some comments are made on the current methodology associated with theBox-Jenkins approach. The three strokes of Identification, Estimation and Verification are considered; and a final stage, that of Interpretation, mentioned. A discussion of whether the approach is practicable is also given.     

Dimensions of the public affairs/government relations function in major American corporations

The public affairs/government relations (PA/GR) function appears to be growing in importance in large corporations. A survey of the 500 largest U.S. industrial concerns was undertaken to ascertain their views and practices with regard to the PA/GR function. 130 of the 163 firms responding to the survey have a formalized PA/GR function in place. Survey data supports the idea that top corporate decision makers are allocating significant staff and decision making authority to the PA/GR function and that this activity differs significantly from the traditional lobbying and public affairs activities of the past.     

A Multivariate Linear Regression Test for the Arbitrage Pricing Theory

A test for the arbitrage pricing theory which employs a multivariate linear regression model is developed. Given a sample of return premiums for a set of N assets which includes a subset of k linearly independent portfolios, the k factor APT hypothesis is accepted if the intercept term is zero in the multivariate regression of the $(N?k)$ returns on the k portfolios. The test may be carried out simply, by using univariate multiple regression software. The relation of this test to the concept of performance potential and Sharpe's measure of performance is also discussed. If the performance potential of the k portfolios is not significantly less than the performance potential of the complete set of N assets, then the k factor APT hypothesis is accepted.