Measuring graduation rates at 200 percent of the expected time to graduate instead of 150 percent has an impact, but a relatively small one, according to a study released Thursday by the National Center for Education Statistics. The standard federal measure is 150 percent (or six years for a bachelor's degree and three years for an associate degree), but some have suggested that a longer time frame would show many more students finishing. The study found that while there are modest gains, they are smaller than those seen by measuring at 150 percent of expected time instead of 100 percent. At public, four-year colleges, the average gain by measuring rates at eight years over six is 4 percentage points, but the gain from four years to six years is 26 percentage points. For community colleges, the gain by going from three to four years is six percentage points, while the growth from two years to three is 11 percentage points.