The approximate coordinate exchange algorithm for Bayesian optimal design of experiments

Optimal Bayesian experimental design typically involves maximising the expectation, with respect to the joint distribution of parameters and responses, of some appropriately chosen utility function. This objective function is usually not available in closed form and the design space can be of high dimensionality. The approximate coordinate exchange algorithm is proposed for this maximisation problem where a Gaussian process emulator is used to approximate the objective function. The algorithm can be used for arbitrary utility functions meaning we can consider fully Bayesian optimal design. It can also be used for those utility functions that result in pseudo-Bayesian designs such as the popular Bayesian D-optimality. The algorithm is demonstrated on a range of examples

Optimal designs for multivariable spline models

In this paper, we investigate optimal designs for multivariate additive spline regressionmodels. We assume that the knot locations are unknown, so must be estimated from thedata. In this situation, the Fisher information for the full parameter vector depends on theunknown knot locations, resulting in a non-linear design problem. We show that locally,Bayesian and maximin D-optimal designs can be found as the products of the optimaldesigns in one dimension. A similar result is proven for Q-optimality in the class of allproduct design

Multivariate emulation of computer simulators: model selection and diagnostics with application to a humanitarian relief model

We present a common framework for Bayesian emulation methodologies for multivariate-output simulators, or computer models, that employ either parametric linear models or nonparametric Gaussian processes. Novel diagnostics suitable for multivariate covariance-separable emulators are developed and techniques to improve the adequacy of an emulator are discussed and implemented. A variety of emulators are compared for a humanitarian relief simulator, modelling aid missions to Sicily after a volcanic eruption and earthquake, and a sensitivity analysis is conducted to determine the sensitivity of the simulator output to changes in the input variables. The results from parametric and nonparametric emulators are compared in terms of prediction accuracy, uncertainty quantification and scientific interpretability

Evidence-Based Psychosocial Treatments for Pediatric Body-Focused Repetitive Behavior Disorders

Habits, such as hair pulling and thumb sucking, have recently been grouped into a category of clinical conditions called body-focused repetitive behavior disorders (BFRBDs). These behaviors are common in children and, at extreme levels, can cause physical and psychological damage. This article reviews the evidence base for psychosocial treatment of pediatric BFRBDs. A review of academic databases and published reviews revealed 60 studies on psychosocial treatments for pediatric BFRBDs, 23 of which were deemed suitable for review. Based on stringent methodological and evidence base criteria, we provided recommendations for each specific BFRBD. Individual behavior therapy proved probably efficacious for thumb sucking, possibly efficacious for several conditions, and experimental for nail biting. Individual and multicomponent cognitive-behavioral therapy was named experimental for trichotillomania and nail biting, respectively. No treatment met criteria for well-established status in the treatment of any BFRBD. Recommendations for clinicians are discussed. Reasons for the limitations of existing research in children and adolescents are explored. Several recommendations are presented for future pediatric treatment research on BFRBDs

The collision and coalescence of water droplets

Imperial Users onl