Tests and Confidence Intervals for an Extended Variance Component Using the Modified Likelihood Ratio Statistic

Abstract.  The large deviation modified likelihood ratio statistic is studied for testing a variance component equal to a specified value. Formulas are presented in the general balanced case, whereas in the unbalanced case only the one-way random effects model is studied. Simulation studies are presented, showing that the normal approximation to the large deviation modified likelihood ratio statistic gives confidence intervals for variance components with coverage probabilities very close to the nominal confidence coefficient.     

Improving the Efficiency of the Nelson–Aalen Estimator: the Naive Local Constant Estimator

Abstract.  The Nelson–Aalen estimator is well known to be an asymptotically efficient estimator of the cumulative hazard function, see Andersen et al. ( Statistical models based on counting processes , Springer-Verlag, New York, 1993) among many others. In this paper, we show that the efficiency of the Nelson–Aalen estimator can be considerably improved by using more information in the estimation process than the traditional Nelson–Aalen estimator uses. While our approach results in a biased estimator, the variance improvement is substantial. By optimizing the balance between the bias loss and the variance improvement, we obtain results on the efficiency gain. Several examples for known failure time distributions are used to illustrate these ideas.     

Situational production management: a practical theory for the development and application of production management

Discussions in journals and at conferences often nurture the dream of the ultimate method which may be applied successfully to all situations. Yet everybody knows that ‘it all depends’ and that situational factors determine which methods and systems are appropriate. This paper sets forth to outline a practical theory of a situational approach to production management. Any improvement of production management is seen as a dialogue between identification of the production management task, on the one hand, and specifying a solution system, on the other. A few concepts are introduced to provide practical methods for carrying out an improvement process; in particular, the nature of the production management task is addressed. The implications of the situational theory to be presented are discussed for three levels of application, respectively, the general level, the industry level, and the level of an individual industrial enterprise. It is further argued that the three levels are interdependent and that their joint application may stimulate both the theoretical and practical development of production management.     

INEFFICIENCY AS A STRATEGIC DEVICE IN GROUP CONTESTS AGAINST DOMINANT OPPONENTS

Contests between groups are prone to intra‐group externalities (free‐riding). Yet, costless incentive schemes that entirely avoid free‐riding within a group might be undesirable, both individually and socially. In contests between two groups, a relatively weak (i.e., small or unproductive) group will optimally not implement them because they compound differences in strength between groups. If the groups are of relatively similar strengths, they are both worse off when they rein in their intra‐group externalities compared to a situation where they do not. If groups' strengths differ sufficiently, the relatively strong group benefits at the expense of the relatively weak one. (JEL Z13, D72, N40, D74)     

Managing seasonal fluctuations in demand. Practice and experience of selected industrial enterprises

Principles and methods of production management only seldom address the issue of seasonal variation. Yet, many industrial enterprises are confronted with heavy fluctuations over the year. This article reports on an industrial study of methods developed and applied in six Danish industrial enterprises. The methods represent different approaches to the management of seasonal variation and they often challenge traditions and call for a mental shift on the part of both management and workers.     

Comparing Conditional Quantile Curves

Abstract. We consider the problem of testing the equality of J quantile curves from independent samples. A test statistic based on an L²‐distance between non‐crossing non‐parametric estimates of the quantile curves from the individual samples is proposed. Asymptotic normality of this statistic is established under the null hypothesis, local and fixed alternatives, and the finite sample properties of a bootstrap‐based version of this test statistic are investigated by means of a simulation study.