/ Dictionary / Index D decision theory: Meaning and Definition of Find definitions for: deci'sion the"ory Pronunciation: [key] — Statistics. Statistics. the theory of making decisions based on assigning probabilities to various factors and assigning numerical consequences to the outcome. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. decision procedure decision tree Related Content Daily Word Quiz: agitated Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language