Prediction of Crime and Recidivism

The prediction process requires that a person be assessed twice. At Time One, he or she is placed into certain categories that are believed, for whatever reason, to relate to the behavior being predicted. If one is interested in predicting how well a person will do in college, the categories might be grades in high school, letters from teachers (rated, for example, as "very good," "good," or "poor"), and the quality of the essay written for the application (perhaps scored on a scale of 1 through 10). These are all predictor variables—categories consisting of different levels that are presumed to be relevant to what is being predicted. For criminal behavior, the predictor variables might include frequency of past criminal acts, age, or degree of impulse control.

At some specified later point, Time Two, another assessment of the person is performed to ascertain whether he or she has or has not done what was predicted. This entails assessing the person on one or more criterion variables. For predicting success in college, the criterion variables might be college grades, class rank, or whether or not the person obtained a job in the field that person wanted (scored simply as "yes" or "no"). For criminal behavior, the criterion variables may include self-report, either arrest or conviction for certain crimes, or involuntary commitment to a mental hospital as a person dangerous to others.