Carem C. Fabris Alex Alves Freitas Discovering Surprising Instances of Simpson's Paradox in Hierarchical Multidimensional Data. 27-49 2006 2 IJDWM 1 http://www.igi-pub.com/articles/details.asp?ID=5440 db/journals/jdwm/ijdwm2.html#FabrisF06