Verallgemeinerte DEA-Modelle zur Performanceanalyse

Dyckhoff and Allen derived a generalisation of Data Envelopment Analysis (DEA) in order to measure ecological efficiency. This approach distinguishes between inputs and outputs of an activity on the one hand and their impact on the relevant evaluation criteria—referred to as efforts and benefits—on the other hand. Thereby, the current framework of the DEA for analysing the relative performance of productive units is fundamentally extended. The relevance of this framework is not limited to ecological aspects because many essential problems of DEA application can be solved. Against this background, the paper presents a formalisation of the generalised DEA, applies it to the well-known basic DEA models, and concretises these models for linear effort and benefit functions.     

Multinomial Selection Problem: A Study of BEM and AVC Algorithms

The two well-known and widely used multinomial selection procedures Bechhofor, Elmaghraby, and Morse (BEM) and all vector comparison (AVC) are critically compared in applications related to simulation optimization problems.

Two configurations of population probability distributions in which the best system has the greatest probability p _i of yielding the largest value of the performance measure and has or does not have the largest expected performance measure were studied.

The numbers achieved by our simulations clearly show that none of the studied procedures outperform the other in all situations. The user must take into consideration the complexity of the simulations and the performance measure probability distribution properties when deciding which procedure to employ.

An important discovery was that the AVC does not work in populations in which the best system has the greatest probability p _i of yielding the largest value of the performance measure but does not have the largest expected performance measure.     

Principal stratum strategy: Potential role in drug development

A randomized trial allows estimation of the causal effect of an intervention compared to a control in the overall population and in subpopulations defined by baseline characteristics. Often, however, clinical questions also arise regarding the treatment effect in subpopulations of patients, which would experience clinical or disease related events post-randomization. Events that occur after treatment initiation and potentially affect the interpretation or the existence of the measurements are called intercurrent events in the ICH E9(R1) guideline. If the intercurrent event is a consequence of treatment, randomization alone is no longer sufficient to meaningfully estimate the treatment effect. Analyses comparing the subgroups of patients without the intercurrent events for intervention and control will not estimate a causal effect. This is well known, but post-hoc analyses of this kind are commonly performed in drug development. An alternative approach is the principal stratum strategy, which classifies subjects according to their potential occurrence of an intercurrent event on both study arms. We illustrate with examples that questions formulated through principal strata occur naturally in drug development and argue that approaching these questions with the ICH E9(R1) estimand framework has the potential to lead to more transparent assumptions as well as more adequate analyses and conclusions. In addition, we provide an overview of assumptions required for estimation of effects in principal strata. Most of these assumptions are unverifiable and should hence be based on solid scientific understanding. Sensitivity analyses are needed to assess robustness of conclusions.     

Politics of childhood,childrens rights,and intergenerational relations

One of the more decisive questions in the discussion of human living conditions, which then also produces the most diverse answers, concerns the relation between violence and civilization. In this context the treatment of childhood and of childrens rights is a crucial issue of this century. We live in a period of socialism, the womens movement, intercourse, individualism. Are we not entering the period of youth? (Benjamin 1991, p. 9), asked Walter Benjamin 80 years ago, shortly after Ellen Key had program-matically declared The Century of the Child (Key 1978). Aries, in his history of childhood and family life in the Ancien Regime, investigated the generalization of social control and subsequent new forms of intervention into social relations (Aries 1978, pp. 556–8). They concern:     

Designing a non-inferiority study in kidney transplantation: a case study

In organ transplantation, placebo-controlled clinical trials are not possible for ethical reasons, and hence non-inferiority trials are used to evaluate new drugs. Patients with a transplanted kidney typically receive three to four immunosuppressant drugs to prevent organ rejection. In the described case of a non-inferiority trial for one of these immunosuppressants, the dose is changed, and another is replaced by an investigational drug. This test regimen is compared with the active control regimen. Justification for the non-inferiority margin is challenging as the putative placebo has never been studied in a clinical trial. We propose the use of a random-effect meta-regression, where each immunosuppressant component of the regimen enters as a covariate. This allows us to make inference on the difference between the putative placebo and the active control. From this, various methods can then be used to derive the non-inferiority margin. A hybrid of the 95/95 and synthesis approach is suggested. Data from 51 trials with a total of 17,002 patients were used in the meta-regression. Our approach was motivated by a recent large confirmatory trial in kidney transplantation. The results and the methodological documents of this evaluation were submitted to the Food and Drug Administration. The Food and Drug Administration accepted our proposed non-inferiority margin and our rationale.     

A note on multivariate linear regression

In this note, a hypothesis test based on relevant statistical differences is proposed for multivariate linear regression models whose design matrix rank does not equal the number of regression variables. A statistical example is also provided to illustrate the proposed hypothesis test.     

The role of acculturative stress and cultural backgrounds in migrants with pathological gambling

The objective of the present study was to differentiate specific migration-related factors that can account for an increased vulnerability to pathological gambling (PG) among migrants in Germany. One hundred and six gamblers (61 migrants, 45 Germans) with varying degrees of gambling problems participated in the study. We analysed (1) differences between migrants and Germans regarding gambling patterns, severity of gambling problems, motivation and craving; influence of (2) acculturative stress; (3) acceptance and popularity of gambling in the culture of origin on gambling problems; (4) differences between migrants and Germans regarding family gambling and peer gambling; and (5) differences in religiosity and its influence on gambling problems. Results suggest no differences between migrants and Germans regarding gambling patterns and the severity of gambling problems. However, findings indicate that migrants have higher motivation and craving to gamble. Findings further suggest that acculturative stress is associated with more severe gambling problems. In contrast, acceptance and popularity of gambling in the country of origin was not a significant predictor of gambling problems. At the same time, family gambling and peer gambling was significantly more prevalent among migrants, constituting an additional risk factor in the present sample. On the other hand, migrants in the sample benefit more often from a protective influence of religiosity.