A Bayesian Robust IRT Outlier-Detection Model.

In psychometric practice, the parameter estimates of a standard item-response theory (IRT) model can become biased when item-response data, of persons' individual responses to test items, contain outliers relative to the model. Also, the manual removal of outliers can be a time-consuming and difficult task. Besides, removing outliers leads to data information loss in parameter estimation.

Informant similarities, twin studies, and the assessment of externalizing behavior: A meta-analysis.

The purpose of this study was to examine similarity within informant ratings of the externalizing behavior of monozygotic (MZ) and dizygotic (DZ) twin pairs. To do this, we conducted a meta-analysis of correlations within ratings completed by mothers, fathers, teachers, and youth. We retrieved n=204 correlations for MZ twins and n=267 correlations for DZ twins from n=54 studies containing n=55 samples.

A Bayesian nonparametric test of significance chasing biases.

There is a growing concern that much of the published research literature is distorted by the pursuit of statistically significant results. In a seminal article, Ioannidis and Trikalinos (2007, Clinical Trials) proposed an omnibus (I&T) test for significance chasing (SC) biases. This test compares the observed number of studies that report statistically significant results, against their expected number based on study power, assuming a common effect size across studies.

On Bayesian Testing of Additive Conjoint Measurement Axioms Using Synthetic Likelihood.

This article introduces a Bayesian method for testing the axioms of additive conjoint measurement. The method is based on an importance sampling algorithm that performs likelihood-free, approximate Bayesian inference using a synthetic likelihood to overcome the analytical intractability of this testing problem. This new method improves upon previous methods because it provides an omnibus test of the entire hierarchy of cancellation axioms, beyond double cancellation.

A menu-driven software package of Bayesian nonparametric (and parametric) mixed models for regression analysis and density estimation.

Most of applied statistics involves regression analysis of data. In practice, it is important to specify a regression model that has minimal assumptions which are not violated by data, to ensure that statistical inferences from the model are informative and not misleading. This paper presents a stand-alone and menu-driven software package, Bayesian Regression: Nonparametric and Parametric Models, constructed from MATLAB Compiler.

A Bayesian nonparametric meta-analysis model.

In a meta-analysis, it is important to specify a model that adequately describes the effect-size distribution of the underlying population of studies. The conventional normal fixed-effect and normal random-effects models assume a normal effect-size population distribution, conditionally on parameters and covariates. For estimating the mean overall effect size, such models may be adequate, but for prediction, they surely are not if the effect-size distribution exhibits non-normal behavior.

An instrument to evaluate pharmacists' patient counseling on herbal and dietary supplements.

Objective: To develop a measure of pharmacists' patient counseling on herbal and dietary supplements.

Methods: A systematic process was used for item generation, testing, and validation of a measure of pharmacists counseling on herbal and dietary supplements. Because a pharmacist-patient encounter may or may not identify an indication for taking an herb or dietary supplement, the instrument was bifurcated into 2 distinct components: (1) patient counseling in general; and (2) patient counseling related to herbal and dietary supplements.

Scaling sexual behavior or "sexual risk propensity" among men at risk for HIV in Kisumu, Kenya.

We present a scale to measure sexual risk behavior or "sexual risk propensity" to evaluate risk compensation among men engaged in a randomized clinical trial of male circumcision. This statistical approach can be used to represent each respondent's level of sexual risk behavior as the sum of his responses on multiple dichotomous and rating scale (i.e.

Coherent psychometric modelling with Bayesian nonparametrics.

In this paper we argue that model selection, as commonly practised in psychometrics, violates certain principles of coherence. On the other hand, we show that Bayesian nonparametrics provides a coherent basis for model selection, through the use of a 'nonparametric' prior distribution that has a large support on the space of sampling distributions. We illustrate model selection under the Bayesian nonparametric approach, through the analysis of real questionnaire data.

Measuring and comparing higher education quality between countries worldwide.

The purpose of this investigation is to establish a unidimensional interval scale for measuring each country on the quality of higher education, based on indicators (items) characterizing various aspects of a country's quality. The data from these indicators are publicly available through the United Nations Educational, Scientific, and Cultural Organization (UNESCO), for all countries worldwide. Currently, a country's quality of higher education is summarized by simple descriptive statistics of these many indicators, and there seems to be a need to combine these results into a single measure of quality.

The use of the Minimum Data Set to identify depression in the elderly.

Objective: To determine whether depression in the elderly in institutionalized settings could be identified using the mood indicators in the Minimum Data Set (MDS) 2.0 (Section E1, Items A-P).

Design: Descriptive study.

A student-initiated elective on end-of-life care: a unique perspective.

Traditionally, curriculum change is a faculty responsibility. However, a first-year medical student, inspired by previous interactions with cancer patients and disillusioned with her education on the physician's role at the end of life, successfully initiated and sustained an end-of-life curriculum change. This article briefly describes the Preceptorship on End of Life Care and then shifts focus to five key dilemmas associated with student-led curriculum change.