Illustrating Bayesian Evaluation of Informative Hypotheses for Regression Models

In the present article we illustrate a Bayesian method of evaluating informative hypotheses for regression models. Our main aim is to make this method accessible to psychological researchers without a mathematical or Bayesian background. The use of informative hypotheses is illustrated using two datasets from psychological research. In addition, we analyze generated datasets with manipulated differences in effect size to investigate how Bayesian hypothesis evaluation performs when the magnitude of an effect changes. After reading this article the reader is able to evaluate his or her own informative hypotheses

Analyzing indirect effects in cluster randomized trials: The effect of estimation method, number of groups and group sizes on accuracy and power

Cluster randomized trials assess the effect of an intervention that is carried out at the group or cluster level. Ajzen's theory of planned behavior is often used to model the effect of the intervention as an indirect effect mediated in turn by attitude, norms and behavioral intention. Structural equation modeling (SEM) is the technique of choice to estimate indirect effects and their significance. However, this is a large sample technique, and its application in a cluster randomized trial assumes a relatively large number of clusters. In practice, the number of clusters in these studies tends to be relatively small, e.g., much less than fifty. This study uses simulation methods to find the lowest number of clusters needed when multilevel SEM is used to estimate the indirect effect. Maximum likelihood estimation is compared to Bayesian analysis, with the central quality criteria being accuracy of the point estimate and the confidence interval. We also investigate the power of the test for the indirect effect. We conclude that Bayes estimation works well with much smaller cluster level sample sizes such as 20 cases than maximum likelihood estimation; although the bias is larger the coverage is much better. When only 5-10 clusters are available per treatment condition even with Bayesian estimation problems occur

Methods for Early Assessment of the Societal Value of Health Technologies: A Scoping Review and Proposal for Classification

Objectives: Early assessments of health technologies help to better align and integrate their development and assessment. Such assessments can take many forms and serve different purposes, hampering users in their selection of the most appropriate method for a specific goal. The aim of this scoping review was to structure the large set of methods according to their specific goal. Methods: A scoping review was conducted using PubMed and reference lists of retrieved articles, to identify review studies with a methodological focus. From the included reviews, all individual methods were listed. Based on additional literature and examples, we extracted the specific goal of each method. All goals were clustered to derive a set of subclasses and methods were grouped into these subclasses. Results: Of the 404 screened, 5 reviews were included, and 1 was added when searching reference lists. The reviews described 56 methods, of which 43 (77%) were included and classified as methods to (1) explore the nature and magnitude of the problem, (2) estimate the nature and magnitude of the expected (societal) value, (3) identify conditions for the potential value to materialize, and (4) help develop and design the type of research that is needed. Conclusions: The wide range of methods for exploring the societal value of health technologies at an early stage of development can be subdivided into a limited number of classes, distinguishing methods according to their specific objective. This facilitates selection of appropriate methods, depending on the specific needs and aims

Additional Information: Facing off with Scylla and Charybdis: a comparison of scalar, partial, and the novel possibility of approximate measurement invariance

On this webpage additional information for the paper “Facing off with Scylla and Charybdis: a comparison of scalar, partial, and the novel possibility of approximate measurement invariance” will be published. The paper can be found at: http://journal.frontiersin.org/article/10.3389/fpsyg.2013.00770/ful