Marie Wiberg is Professor of Statistics with a specialty in psychometrics at Umeå University, Sweden. Her research interests include test equating, applied statistics, large-scale assessments and psychometrics in general.

Steven Culpepper is Associate Professor at the Department of Statistics, University of Illinois at Urbana-Champaign. His research interests include Bayesian statistics, cognitive diagnosis, large-scale assessments and psychometrics in general.

Rianne Janssen is Associate Professor at the Faculty of Psychology and Educational Sciences, KU Leuven in Belgium. She is chiefly interested in educational measurement and psychometrics, especially for applications in large-scale student assessments.

Jorge González is Associate Professor at the Faculty of Mathematics, Pontificia Universidad Católica de Chile. His research interests include statistical modeling of social sciences data, particularly in the fieldsof educational measurement and psychometrics.

Dylan Molenaar is Assistant Professor at the Department of Psychology, University of Amsterdam, the Netherlands, where he received his PhD degree in Psychology in 2012 for a thesis on "Testing distributional assumptions in psychometric measurement models with substantive applications in psychology." His research interests include item response theory, factor analysis, response time modeling, mixture modeling, modeling of intelligence test data, and modeling of genotype by means of environmental interactions.