The only way to make a certain prediction of cause and effect is to study the life in which the causes operate, and not a thousand other lives. Psychological causation is always personal and never actuarial .
Probability is based on the frequentist notion of repeated trials.
However, Allport did feel that if we knew all the variables that are related to recidivism then we would be able to predict the delinquent's outcome with near certainty. If you score above 50 points you have a 1 in 30 chance of being admitted to graduate school. If you score above 30 points you have a 1 in a 100 chance of getting into graduate school. Formula used by Penn State Clinical Ph.D. Program in 1978 for admission.