Matthijs J Warrens

Position Assistant professor Institute of Psychology Unit Methodology and Statistics Leiden University warrens@fsw.leidenuniv.nl Education 2009-now BSc student Mathematics, Leiden University 2010 Propedeutic examination Mathematics, Leiden University 2008 PhD Social Sciences, Leiden University 2002 MSc Psychology, Leiden University 2000 Propedeutic examination Psychology, Leiden University Links Webpage at Psychology, Curriculum Vitae, PhD thesis Publications

In press	Erdmann TP, De Mast J, Warrens MJ, Some common errors of experimental design, interpretation and inference in agreement studies. Statistical Methods in Medical Research Journal
2012	Warrens MJ, Some paradoxical results for the quadratically weighted kappa. Psychometrika 77:315-323 Journal LUR Warrens MJ, Cohen's linearly weighted kappa is a weighted average. Advances in Data Analysis and Classification 6:67-79 Journal LUR Warrens MJ, Equivalences of weighted kappas for multiple raters. Statistical Methodology 9:407-422 Journal Warrens MJ, The effect of combining categories on Bennett, Alpert and Goldstein's S. Statistical Methodology 9:341-352 Journal Warrens MJ, A family of multi-rater kappas that can always be increased and decreased by combining categories. Statistical Methodology 9:330-340 Journal Warrens MJ, Cohen's quadratically weighted kappa is higher than linearly weighted kappa for tridiagonal agreement tables. Statistical Methodology 9:440-444 Journal
2011	Warrens MJ, Cohen's kappa is a weighted average. Statistical Methodology 8:473-484. Journal Warrens MJ, Cohen's linearly weighted kappa is a weighted average of 2x2 kappas. Psychometrika 76:471-486. Journal LUR Warrens MJ, Chance-corrected measures for 2x2 tables that coincide with weighted kappa. British Journal of Mathematical and Statistical Psychology 64:355-365. Journal Warrens MJ, Weighted kappa is higher than Cohen's kappa for tridiagonal agreement tables. Statistical Methodology 8:268-272. Journal
2010	Warrens MJ, A formal proof of a paradox associated with Cohen's kappa. Journal of Classification 27: 322-332. Journal LUR Warrens MJ, Inequalities between multi-rater kappas. Advances in Data Analysis and Classification 4:271-286. Journal LUR Warrens MJ, Cohen's kappa can always be increased and decreased by combining categories. Statistical Methodology 7:673-677. Journal Warrens MJ, A Kraemer-type rescaling that transforms the odds ratio into the weighted kappa coefficient. Psychometrika 75:328-330. Journal LUR Warrens MJ, Inequalities between kappa and kappa-like statistics for kxk tables. Psychometrika 75:176-185. Journal LUR Warrens MJ, n-Way metrics. Journal of Classification 27:173-190. Journal LUR
2009	Warrens MJ, k-Adic similarity coefficients for binary (presence/absence) data. Journal of Classification 26:227-245. Journal LUR Warrens MJ, On Robinsonian dissimilarities, the consecutive ones property and latent variable models. Advances in Data Analysis and Classification 3:169-184. Journal LUR Warrens MJ, A comment on ``The J index as a measure of nominal scale response agreement.'' Applied Psychological Measurement 33:486-487. Journal LUR Warrens MJ, Heiser WJ, Diagnostics for regression dependence in tables re-ordered by the dominant correspondence analysis solution. Computational Statistics and Data Analysis 53:3139-3144. Journal LUR
2008	Warrens MJ, On similarity coefficients for 2x2 tables and correction for chance. Psychometrika 73:487-502. Journal LUR Warrens MJ, On association coefficients for 2x2 tables and properties that do not depend on the marginal distributions. Psychometrika 73:777-789. Journal LUR Warrens MJ, On the equivalence of Cohen's kappa and the Hubert-Arabie adjusted Rand index. Journal of Classification 25:177-183. Journal LUR Warrens MJ, On the indeterminacy of resemblance measures for binary (presence/absence) data. Journal of Classification 25:125-136. Journal LUR Warrens MJ, Bounds of resemblance measures for binary (presence/absence) variables. Journal of Classification 25:195-208. Journal LUR Warrens MJ, On multi-way metricity, minimality and diagonal planes. Advances in Data Analysis and Classification 2:109-119. Journal LUR