In a large-scale selection program, there are 3 parties: 1). applicants; 2) the selector; and 3) the employer. An attempt has been made to describe quantitatively what risks the parties are going through of having installed a selection program. The principal measuring instruments are the applicants' and selector's operating characteristics (OC curves); the efficiency index of having a selection procedure, the quality gain diagram; and the cost-utility diagram. These are discussed in part 1--the mathematical model. Equations are given. Included in section 2, the statistical estimation, are the confidence belt of the operating characteristics, the standard error of the mean criterion score of selectees, and the standard error of the predicted number of successful selectees at score level x. (SGK).