When parents in Simsbury, Connecticut, became concerned that their high school’s demanding grading system was jeopardizing students’ chances for admissions into elite colleges, a local nuclear engineer decided to do something about it. Robert M. Hartranft, a self-proclaimed workaholic who was forced into early retirement because of Parkinson’s disease, developed an extensive mathematical model to compare school grading systems across the nation by tracking grade-point averages against SAT scores. The model can thus purportedly show, for example, that a B at Simsbury High School is equivalent to an A at many other schools. Simsbury High now includes the comparison, called the “g.p.a. plot,” in students’ college application materials, and school officials believe it may have helped raised Simsbury students' admission rates in recent years. The reaction of college admissions officers is mixed, however. While at least one praises Hartranft’s method for providing context for student grades, others question its reliance on SAT scores. “I used to be a teacher,” says Robert S. Clagett, dean of admissions at Middlebury College, “and I would hate to have somebody take my standards and arbitrarily correlate it to the SAT. It’s attempting to make a science out of what is very much an art.” Even so, Hartranfta man who prefers hard data to intuitionargues he’s developed the most effective grade-comparison method available. “I’m giving you a G.P.S. navigation system, as opposed to scraps of maps,” he says.