of charter school authorizers, including the removal of poor-quality authorizers, (ii) improve the quality of student performance data with more longitudinal student-linked data and multiple measures of school performance, and (iii) clarify state laws related to charter school closure, especially the treatment of displaced students. All but 17% of charter school students show no improvement when compared to a heuristically modeled virtual twin traditional public school. Educational gains from switching to charter schools from public schools have on average been shown to be "small or insignificant" (Zimmer, et al.) and tend to decline over a span of time (Byrnes). Charter schools provided no substantial improvement in students' educational outcomes that could not be accounted for in a public school setting (Gleason, Clark and Clark Tuttle). Attrition rates for teachers in charter schools have shown annual rates as high as 40%. Students also tend to move from charter schools prior to graduation more often than do students in public schools (Finch, Lapsley and Baker-Boudissa). Charter schools are often regarded as an outgrowth of the Powell Manifesto advocating corporate domination of the American democratic process and are considered to represent vested interests' attempts to mold public opinion via public school education and to claim a share of this $500–600 billion-dollar industry. Scalability Whether the charter school model can be scaled up to the size of a public noncharter school system has been questioned, when teaching demands more from teachers and many noncharter teachers are apparently unable to teach in the way charters seek, as has been suggested by Arne Duncan, U.S. Secretary of Education, Diane Ravitch, education historian and former assistant U.S. education secretary, Mark Roosevelt, former schools chief for Pittsburgh, Penn., U.S., and Dave Levin, of the KIPP charters However, some, such as Eva Moskowitz of Success Academy Charter Schools, believe that the model can be scaled up. Exploitation by for-profit entities Critics have accused for-profit entities, (education management organizations, EMOs) and private foundations such as the Bill and Melinda Gates Foundation, the Eli and Edythe Broad Foundation, and the Walton Family Foundation of funding Charter school initiatives to undermine public education and turn education into a "business model" which can make a profit. According to activist Jonathan Kozol, education is seen as one of the biggest market opportunities in America or "the big enchilada". Shift from progressive to conservative movement Charters were originally a progressive movement (called the "small schools"