 There is a high variability in the quality and success of charter schools across the nation.A high-profile report from the American Federation of Teachers (2002), for example, argued that many charter school authorizers have failed to hold the administrators and teachers accountable, leaving some students to languish in low-performing schools.Another concern of critics is that charters are more racially segregated than traditional public schools, thus denying students the educational "benefits associated with attending diverse schools".