Combining Human Judgment and Multiple Regression Combining Human Judgment and Multiple Regression Richard B. Darlington Prediction is one of the fundamental purposes of science, and indeed the need to predict or estimate unknown values arises throughout life. Medical diagnosis is really a prediction problem, since the future usually reveals which diagnosis was correct. Predicting what consumers will buy is fundamental to virtually any business. Predicting the number of people who will retire or apply for unemployment benefits or welfare is necessary for rational public policy.
Prediction arises in many other contexts as well.
An enormous amount of prediction is made by human judgment. Members of a parole board read an inmate's case history and attempt to predict whether he will commit more crimes if released. Physicians study a list of symptoms and circumstances to make a diagnosis. However, extensive research over the last 40 years indicates that when you have a database of at least 50 previous cases for which you have the data used in making the predictions, and you know the ultimate outcome for those cases, and those cases are representative of the current sample of cases, then you can enter those previous cases into a regression or a variant of regression, and generally use the results of that analysis to make more accurate predictions of future cases than can be made by human judgment alone. Most of these authors are psychologists, but they summarize some 90 studies covering an enormous range of topics, from meteoreology to medicine to economics.