On the practice of dichotomization of quantitative variables
Psychological Methods (2002) - Comment
doi: 10.1037/1082-989x.7.1.19  issn: 1939-1463  issn: 1082-989x  pubmed: 11928888 

Robert C. MacCallum, Shaobo Zhang, Kristopher J. Preacher, Derek D. Rucker