The current state of Bayesian methods in nonclinical pharmaceutical statistics: Survey results and recommendations from the DIA/ASA-BIOP Nonclinical Bayesian Working Group

The use of Bayesian methods to support pharmaceutical product development has grown in recent years. In clinical statistics, the drive to provide faster access for patients to medical treatments has led to a heightened focus by industry and regulatory authorities on innovative clinical trial designs, including those that apply Bayesian methods. In nonclinical statistics, Bayesian applications have also made advances. However, they have been embraced far more slowly in the nonclinical area than in the clinical counterpart. In this article, we explore some of the reasons for this slower rate of adoption. We also present the results of a survey conducted for the purpose of understanding the current state of Bayesian application in nonclinical areas and for identifying areas of priority for the DIA/ASA-BIOP Nonclinical Bayesian Working Group. The survey explored current usage, hurdles, perceptions, and training needs for Bayesian methods among nonclinical statisticians. Based on the survey results, a set of recommendations is provided to help guide the future advancement of Bayesian applications in nonclinical pharmaceutical statistics.     

Technology adoption and training practices as a constrained shortest path problem

Technology adoption is not a new venue for research. Much work of decision modeling, diffusion of new technology and statistical analysis of survey data has been done. Some studies focus on finding the optimal forms of technology to adopt within a complementarity framework, but there is no mention of finding an optimal path from a firm's current state to its optimal state. This represents a significant gap in the literature. The paper applies a constrained shortest path problem to training and technology adoption decisions by firms. Given the current set of training and technology adoption the method solves for what technology/practice should be adopted or removed from the complete set of combinations and in what order so as to maximize performance subject to budget constraints. To the authors' knowledge, this is the first application of the constrained shortest path problem to technology adoption decisions.     

The Relation between Accounting Conservatism and Corporate Social Performance: An Empirical Investigation

Accounting conservatism and corporate social responsibility have received much attention in the recent literature. The current study draws upon Watts, who recognizes that one role of conservatism is to reduce the likelihood of excess wealth transfers to its stakeholder groups and Post et al., who assert that a key aspect of positive corporate social performance is the (equitable) distribution of corporate wealth. Accordingly, this study empirically investigates and finds a positive relation between conservatism and strong social performance.     

Heterogeneous Firm Responses to Rising Teenage Wages

Substantial youth minimum wage changes in New Zealand between 2000 and 2007 raised teenage average wages by 5–10 per cent relative to those for adults. We use Statistics New Zealand's Linked Employer–Employee Database (LEED) to examine whether firms' teenage labour demand responses to these changes are greater for firms with higher teenage‐employment share. We find evidence that high teen‐employers reduced their teen employment relative to other firms and had lower survival rates over the period. However, firms that entered the main teen‐employment industries had higher teen‐employment shares than continuing firms. The results are consistent with endogenous technology adoption in response to non‐marginal changes in relative wages.     

A modification of the kruskal-wallis statistic for the generalized behrens-fisher problem

The problem of testing the equality of the medians of several populations is considered. Standard distribution-free procedures for this problem require that the populations have the same shape in order to maintain their nominal significance level, ever asymptotically, under the null hypothesis of equal medians , A modification of the Kruskal-Wallis test statistic is proposed which is exactly distribution-free under the usual nonparanetric asswnption that the continuous populations are identical with any shape. It is asymptotically distribution-free when the Continuous populations are asswned to be syrmnetric with equal medians.     

A note on Stein's lemma for multivariate elliptical distributions

When two random variables are bivariate normally distributed Stein's original lemma allows to conveniently express the covariance of the first variable with a function of the second. Landsman and Neslehova (2008) extend this seminal result to the family of multivariate elliptical distributions. In this paper we use the technique of conditioning to provide a more elegant proof for their result. In doing so, we also present a new proof for the classical linear regression result that holds for the elliptical family.     

Adaptive web sampling in ecology

Adaptive sampling strategies for ecological and environmental studies are described in this paper. The motivations for adaptive sampling are discussed. Developments in this area over recent decades are reviewed. Adaptive cluster sampling and a number of its variations are described. The newer class of adaptive web sampling designs and their spatial sampling uses are discussed. Case studies in the use of adaptive sampling strategies with ecological populations are cited. The nature of optimal sampling strategies is described. Design-based and model-based approaches to inference with adaptive sampling strategies are summarized.     

A a comparison of the markov chain and the integral equation approaches for evaluating the run length distribution of quality control charts

Two methods that are often used to evaluate the run length distribution of quality control charts are the Markov chain and integral equation approaches. Both methods have been used to evaluate the cumulative sum (CUSUM) charts and the exponentially weighted moving average (EWMA) control charts. The Markov chain approach involves "discretiz-ing" the possible values which can be plotted. Using properties of finite Markov chains, expressions for the distribution of the run length, and for the average run length (ARL), can be obtained. For the CUSUM and EWMA charts there exist integral equations whose solution gives the ARL. Approximate methods can then be used to solve the integral equation. In this article we show that if the product midpoint rule is used to approximate the integral in the integral equation, then both approaches yield the same approximations for the ARL. In addition we show that the recursive expressions for the probability functions are the same for the two approaches. These results establish the integral equation approach as preferable whenever an integral equation can be found