Empirical evaluation of the implementation of the EMA guideline on missing data in confirmatory clinical trials: Specification of mixed models for longitudinal data in study protocols

In confirmatory clinical trials, the prespecification of the primary analysis model is a universally accepted scientific principle to allow strict control of the type I error. Consequently, both the ICH E9 guideline and the European Medicines Agency (EMA) guideline on missing data in confirmatory clinical trials require that the primary analysis model is defined unambiguously. This requirement applies to mixed models for longitudinal data handling missing data implicitly. To evaluate the compliance with the EMA guideline, we evaluated the model specifications in those clinical study protocols from development phases II and III submitted between 2015 and 2018 to the Ethics Committee at Hannover Medical School under the German Medicinal Products Act, which planned to use a mixed model for longitudinal data in the confirmatory testing strategy. Overall, 39 trials from different types of sponsors and a wide range of therapeutic areas were evaluated. While nearly all protocols specify the fixed and random effects of the analysis model (95%), only 77% give the structure of the covariance matrix used for modeling the repeated measurements. Moreover, the testing method (36%), the estimation method (28%), the computation method (3%), and the fallback strategy (18%) are given by less than half the study protocols. Subgroup analyses indicate that these findings are universal and not specific to clinical trial phases or size of company. Altogether, our results show that guideline compliance is to various degrees poor and consequently, strict type I error rate control at the intended level is not guaranteed.     

Objective Bayesian analysis of counting experiments with correlated sources of background

Searches for faint signals in counting experiments are often encountered in particle physics and astrophysics, as well as in other fields. Many problems can be reduced to the case of a model with independent and Poisson-distributed signal and background. Often several background contributions are present at the same time, possibly correlated. We provide the analytic solution of the statistical inference problem of estimating the signal in the presence of multiple backgrounds, in the framework of objective Bayes statistics. The model can be written in the form of a product of a single Poisson distribution with a multinomial distribution. The first is related to the total number of events, whereas the latter describes the fraction of events coming from each individual source. Correlations among different backgrounds can be included in the inference problem by a suitable choice of the priors.     

Bounds for the traveling salesman paths of two-dimensional modular lattices

We present tight upper and lower bounds for the traveling salesman path through the points of two-dimensional modular lattices. We use these results to bound the traveling salesman path of two-dimensional Kronecker point sets. Our results rely on earlier work on shortest vectors in lattices as well as on the strong convergence of Jacobi–Perron type algorithms.     

Writing Distinction – Eine illegitime Kultur als subkulturelles Feld

Graffiti is an illegitimate culture, yet with high potential for distinction and abstract aesthetic principles. The article considers these characteristics as result of the process of the autonomization of graffiti as subcultural field and aims to reconstruct its field logic.     

Resolving conflict over salespeople’s brand adoption in franchised channels of distribution

Many franchise-based retail outlets offer both the franchisor-owned brand and brands of competitors or independent suppliers. As salespeople may influence customers’ brand choices considerably, an important concern for franchisors is how to raise salespeople’s selling preferences for the franchisor-owned brand. However, the channel administration literature suggests that salespeople may not automatically favor the franchisor’s brand over other brand lines. While a large body of research examines franchise–channel relationships, previous investigations have conspicuously overlooked this channel conflict. In proposing a conceptual model grounded in the behavioral sciences, this study analyzes how franchisors can induce salespeople to advocate their brand by fostering the intention to promote the franchisor-owned brand (IFOB) in customer interaction. The results of an empirical field study show that individual brand promotion depends on factors such as salespeople’s identification with the franchisor and their tenure with the organization, as well as on the franchisor’s prestige and administration of the franchise. Moreover, we find that franchisees’ IFOB transfers to salespeople, but only if franchisees display a charismatic leadership style. We discuss these findings in light of extant theory and empirical evidence and derive several managerially relevant implications for the administration of franchised retail channels.     

Financing Unemployment Benefits: Dismissal versus Employment Taxes

Abstract. This paper investigates the effects of using dismissal taxes to finance unemployment benefits. We compare dismissal and employment taxes in a model with search frictions. Employment taxes give rise to externalities because firms do not take into account the effects their dismissal decisions have on others. These externalities can be tackled by using dismissal taxes to finance unemployment insurance. Taking into account the budget for unemployment insurance, employment taxes can be reduced by more than is necessary to offset the adverse effect of dismissal taxes on the value of the firm. The introduction of dismissal taxes leads to higher job creation and lower unemployment.     

Intra-industry diversification effects under firm-specific contingencies on the demand side

How do firm-specific, demand-related factors influence the relationship between intra-industry diversification (IID) and performance? Recent findings regarding the performance effects of IID depict a complex picture with curvilinear relationships and several contingencies. However, firm-specific contingencies on the demand side have remained unexplored. We analyze how IID relates to firm performance (market share) in the German automotive industry using panel data between 1999 and 2008. We specifically focus on a firm's high-quality brand image as a demand-side contingency. We find support for our hypotheses of complex curvilinear relationships as well as for moderating effects of brand quality. Our results have significant theoretical implications for the IID literature.