 Some argue that Basis focuses too much on standardized testing.Critics also point out that Basis's performance in national ranking systems like the U.S. News & World Report is largely a function of Basis's singular focus on mandatory Advanced Placement (AP) testing, as these ranking systems give great weight to the percentage of students at a school that take the AP tests.Critics also take issue with Basis's attrition rates (senior classes are typically a third to a quarter of the size of the fifth grade class) and argue that Basis achieves good test scores in part by weeding out under-performing students.