Ryan Shaun Joazeiro de Baker Albert T. Corbett Vincent Aleven Improving Contextual Models of Guessing and Slipping with a Trucated Training Set. 67-76 2008 EDM http://www.educationaldatamining.org/EDM2008/uploads/proc/7_Baker_22.pdf conf/edm/2008 db/conf/edm/edm2008.html#BakerCA08