decision theory n (Statistics) statistics the study of strategies for decision-making under conditions of uncertainty in such a way as to maximize the expected utility. See also game theory Collins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014