Testing equality of variances in the analysis of repeated measurements

The problem of comparing the precisions of two instruments using repeated measurements can be cast as an extension of the Pitman-Morgan problem of testing equality of variances of a bivariate normal distribution. Hawkins (1981) decomposes the hypothesis of equal variances in this model into two subhypotheses for which simple tests exist. For the overall hypothesis he proposes to combine the tests of the subhypotheses using Fisher's method and empirically compares the component tests and their combination with the likelihood ratio test. In this paper an attempt is made to resolve some discrepancies and puzzling conclusions in Hawkins's study and to propose simple modifications.
The new tests are compared to the tests discussed by Hawkins and to each other both in terms of the finite sample power (estimated by Monte Carlo simulation) and theoretically in terms of asymptotic relative efficiencies.     

BOOK REVIEWS AND NOTES

Book reviews in this article: G.D.H. COLE AND INDUSTRIAL DEMOCRACY: A REVIEW: The World of Labour Introduction by John Lovell G.D.H. COLE AND INDUSTRIAL DEMOCRACY: A REVIEW: Self-Government in Industry Introduction by J. G. Corina G.D.H. COLE AND INDUSTRIAL DEMOCRACY: A REVIEW: Workshop Organisation Introduction by A. I. Marsh WORKPLACE INDUSTRIAL RELATIONS: Building: Teamwork or Conflict? by L. G. Bayley The Management of Wage Payment Systems by Alan Gillespie Labour Relations on the Docks by M. Jackson ORGANIZATIONAL BEHAVIOUR: Social Psychology of the Work Organisation by A. S. Tannenbaum Organisational Problems in European Manufacture by T. D. Weinshall LABOUR ECONOMICS: Manpower Economics by E. B. Jakubaus and Neil A. Palomba Labour Economics by J. E. King Unemployment and Wage Inflation with Special Reference to Britain and the U.S.A. by J. Taylor UNEMPLOYMENT: Regional Unemployment Differences in Great Britain by P. C. Cheshire Interregional Migration Models and their Application to Great Britain by R. Weeden The Changing Pattern of Employment—Regional Specialisation and Industrial Localisation in Britain by M. Chisholm and J. Oeppen Men Out of Work—A Study of Unemployment in Three English Towns by M. J. Hill, R. M. Harrison, A. V. Sargeant and V. Talbot Do The Poor Want To Work? A Social-Psychological Study of Work Orientation by L. Goodwin Marienthal: The Sociography of an Unemployed Community by M. Jahoda, P. F. Lazarsfeld and H. Zeisel b     

Extraction of an Exhaustible Resource: The Effects on Investment of Several Parameters Being Subject to Uncertainty*

This article shows that the effect on investment of the introduction of uncertainty about the size of one parameter depends on what other parameters are simultaneously uncertain. Further, two parameters may be linked with positive or negative covariances. The covariances are here shown to have important effects on the investor, whether risk neutral or risk averse. Governments are advked to consider policies that affect the covariances of those parameters that are key influences on in vestment.     

Forecasting first births

This study is concerned with one aspect of the family cycle, namely, the transition from young married to young married with small children. The focus is on developing models to forecast entries into this latter stage for the purpose of marketing research. "Using ordinary least squares, forecasting models were estimated for (1) total number of first births, (2) number of white first births, and (3) number of nonwhite first births." Models are estimated for both the United States and California using data from official sources.     

Low information nash equilibria for oligopolistic markets

This paper deals with an infinite horizon n firm oligopoly in which firms are assumed to have incomplete information about one another's actions and profit functions. An equilibrium concept is defined that is similar to the Nash non-cooperative equilibrium, but is suitable for the information assumptions of the model. The equilibrium uses a type of bounded rationality which makes firms' computations relatively easy. This is due to an implicit assumption that computation is costly and a Bayesian approach is prohibitively costly. This low information Nash equilibrium is proved to exist, and, in addition, an adaptive expectations decision process is described which, if followed by all firms, leads to the low information Nash equilibrium.     

Friedman's Money Supply Rule vs. Optimal Interest Rate Policy

Using New Keynesian models, we compare Friedman's k‐percent money supply rule to optimal interest rate setting, with respect to determinacy, stability under learning and optimality. First we review the recent literature: open‐loop interest rate rules are subject to indeterminacy and instability problems, but a properly chosen expectations‐based rule yields determinacy and stability under learning, and implements optimal policy. We show that Friedman's rule also can generate equilibria that are determinate and stable under learning. However, computing the mean quadratic welfare loss, we find for calibrated models that Friedman's rule performs poorly when compared to the optimal interest rate rule.     

Two–step sequential sampling

Choosing the sample size in advance is a familiar problem: often, additional observations appear to be desirable. The final sample size then becomes a random variable, which has rather serious consequences.
Two such sample extension situations will be considered here. In the first situation, the observed sample variance determines whether or not to double the original sample size. In the second situation, the variances observed in two independent samples are compared; their ratio determines the number of additional observations.