The accuracy of any particular procedure for predicting the outcomes of college football games can be evaluated empirically. In the case of a point predictor for the difference in score between
the “home” team and the “visiting” team, it is a simple matter of comparing the predicted differences with the actual differences. Among the criteria that might be adopted in the
empirical evaluation of the point predictor are the following three: (1) Percentage of winners = the percentage of games won by the teams “favored” to win by the prediction procedure; (2) Average absolute error = the average of the absolute values of the quantities obtained by subtracting the actual differences in score (between the home team and the visiting team) from the predicted differences; and (3) Root mean squared error = the square root of the average of the squared values of the quantities obtained by subtracting the actual differences in score from the predicted differences.
Among the various point predictors for the differences in score is that implicit in the betting line. The betting line is the “gold standard.” Its accuracy can serve as a basis for evaluating the accuracy of other point predictors.
There is a website (http://www.thepredictiontracker.com/) maintained by Todd Beck on which a large number of different point predictors are “tracked” and their accuracy over various periods of time is assessed.