The author presents critical comments on a paper by John Siegfried, in which Siegfried reports on a controlled experiment to determine whether the educational experience of being a proctor is sufficiently valuable to justify awarding academic credit. Siegfried argues that a semester of proctoring teaches a student more than a one-semester, upper-level economics course and that credit should be given. Tietenberg disagrees. When two groups of students, comprised of proctors and students in an upper-level course, were given the College Level Examination Program (CLEP), the proctors scored highest. However, Tietenberg claims, the proctors had been exposed to an introductory course which the CLEP content focuses on, while students in upper-level courses dealt in-depth with specific areas of economics which the CLEP is not designed to measure. The educational outputs of the two types of courses are different, and it is difficult for a single instrument to adequately measure the outputs on a one-dimensional scale. In terms of costs and benefits of proctoring, Tietenberg notes that proctoring takes more of a student's time than taking an upper-level elective. His research shows self-pacing effects and workload effects from increased time requirements on Personalized System of Instruction (PSI) students. (AV)