Is the Regression Equation Adequate?-One Criterion

A decision rule often used for the acceptance or rejection of a fitted regression equation is whether or not the regression F ratio exceeds the critical F value. In fact, all this tells us is whether the fitted equation is better than the mean as a predictor. Many times the experimenter's primary interest is how well the fitted equation represents the true model. This paper presents a numerical criterion to help the experimenter evaluate the adequacy of the regression model, in light of both the range of values to be estimated by the equation and the size of the error term. This criterion can be tested utilizing the ordinary regression F ratio but referring to special critical values. An example from the rubber industry illustrates the use of the criterion.