PhD. degree in Statistics from the Université Catholique de Louvain, Belgium (2000). He has been visiting professor at the Faculty of Psychology, K. U. Leuven, Belgium, and at the Center for Econometric and Operational Research CORE. He is one of the professors who founded the Measurement Center MIDE UC, Chile, where applied research and educational services are developed. His research interests are identification problems in models involving latent variables; school effectiveness and value-added models; mathematical statistics; causality in social science; and history of probability and statistics. Currently, he is Full Professor at the Faculty of Mathematics, Pontificia Universidad Católica de Chile; fellow at the Center for Econometric and Operational Research CORE, and Invited Professor at The Economics School of Louvain, Université Catholique de Louvain, Belgium.