Regarding Harold Wolfson’s Nov. 25 column, “Shea High School’s success”: The Rhode Island Department of Education has imposed a new system for local schools to determine graduation rates. Under this system, which the state says is more accurate, Shea High School, in Pawtucket, last spring reported a graduation rate of 50.9 percent. Mr. Wolfson’s piece reported a graduation rate of “more than 80 percent,” which relied on the previous method of calculating the rate.