Median split, k-group split, and optimality in continuous populations

Continuous populations are grouped in many social, economic, medical, or technical fields of research. However, by grouping them, a lot of information provided by the continuous population is lost. Especially the median split, which is still adopted by many researchers, and its generalization to an equiprobable k-group split lead to a high efficiency loss. Here, this loss of information is investigated by analytical and numerical analyses for some typical symmetric and skew population distributions often found in applications. Various distribution parameters, numbers of groups, and split methods are taken from theoretical considerations and real data sets. Losses sometimes in excess of 50% can be reduced by optimal grouping.     

Evaluation of an inter-organizational program for prevention of work-related injuries in a WHO Safe Community

OBJECTIVE: To evaluate the effect of a community-based injury prevention program on work-related injuries. STUDY DESIGN: A population-based quasi-experimental design was used with pre- and post-implementation measurements in an intervention and a control area. The program was based on cross-sectoral participation in detecting and taking action against work-related injuries. Change in the relative risk of injury was estimated by the odds ratio. RESULTS: The relative risk of work-related injury decreased following program exposure, whereas a tendence toward increase was observed in the control area. Middle-aged men accounted for the largest decrease in injury risk. Among the women, a decrease was observed only in the upper middle-aged group. No female-dominated occupational area showed a decrease in injury risk following exposure to the program. CONCLUSION: The study showed that the community-based approach had a general effect on the incidence of work-related injuries.     

The Theory of Global Games on Test: Experimental Analysis of Coordination Games with Public and Private Information

The theory of global games has shown that coordination games with multiple equilibria may have a unique equilibrium if certain parameters of the payoff function are private information instead of common knowledge. We report the results of an experiment designed to test the predictions of this theory. Comparing sessions with common and private information, we observe only small differences in behavior. For common information, subjects coordinate on threshold strategies that deviate from the global game solution towards the payoff‐dominant equilibrium. For private information, thresholds are closer to the global game solution than for common information. Variations in the payoff function affect behavior as predicted by comparative statics of the global game solution. Predictability of coordination points is about the same for both information conditions.     

Kernel Estimation of the Spectral Density of Stationary Random Closed Sets

A non‐parametric kernel estimator of the spectral density of stationary random closed sets is studied. Conditions are derived under which this estimator is asymptotically unbiased and mean‐square consistent. For the planar Boolean model with isotropic compact and convex grains, an averaged version of the kernel estimator is compared with the theoretical spectral density.     

Some remarks on experimental design for estimating the expectation of a stationary random process

For estimation of the mean of a stationary random process the variance-optimal choice of the observation points (the so called experimental design) is considered. For this discrete and continuous designs are introduced, some known results of process statistics are interpreted to experimental design and a proposal for simplification of the minimization problem is offered, moreover it is proved, that for monotone decreasing eovarianee functions a design, for which the points near the ends of the observation interval are more dense than in the middle, is better than the equidistant design.