What matters more than class size and spending in student achievement? Intensive tutoring.

I found Ty's piece so interesting that I went to the National Bureau of Economic Research and read "What Can We Learn from Charter School Lotteries?" The researchers looked at successful charters that admit students by lottery since they have more applicants than seats.

After pooling the data from 113 such schools and examining practices, the authors conclude “...intensive tutoring is the only characteristic that remains significant in improving student performance. Tutoring offered at charter schools is typically more intense than tutoring offered at traditional public schools. Charter schools often use paid tutors, add tutoring on top of already long school days, and require all students to participate. This finding about the importance of tutoring is in line with other recent evidence pointing to dramatic gains from intensive tutoring on its own, suggesting a good place to start for effective and practical reform at traditional public schools.”

The 63-page paper has other interesting stuff. Here are excerpts of some of it:

•Overall, once one accounts for surrounding neighborhood and school characteristics, many of the specific charter school practices are no longer associated with student improvement. The main exception is intensive tutoring. Its estimated impact remains large and relatively stable, especially in math, even when conditioning on other charter school characteristics.

•In line with previous studies, we find no evidence that differences in class size, per pupil expenditures, or teacher certification explain charter school effectiveness. The “No Excuses” explanatory factor that remains significant after controlling for fallback school performance (even for nonurban schools only) is whether a charter has an intensive tutoring program (though the effect of high suspension rates is close to significant).

•A charter school which attracts students who would have otherwise attended a particularly poor-performing traditional public school would appear more effective than an identical charter school that draws students who would have otherwise attended a better performing school. Estimates of charter school impacts should therefore be interpreted relative to the experience of students who lose the lottery at that school. As mentioned earlier, Angrist et al. (2013) find stark differences in the gain that can be attributed to a charter school according to whether the school is located in an urban or nonurban setting. The large positive effects from the Massachusetts studies are concentrated among the urban charter schools, while nonurban charters are generally ineffective and may even reduce achievement for some.

•Also, charter schools that are more likely to locate in highly segregated and disadvantaged areas tend to be “No Excuses” schools, while nonurban charter schools, in contrast, tend to emphasize other priorities, such as performing arts, interdisciplinary group projects, field work, or customized instruction.

•Lottery studies that use admissions data from identifiable schools, like KIPP Lynn, UP Academy, SEED, and the Promise Academy charter schools, allow for a more in-depth analysis of the mechanisms behind why some types of charter schools are more effective than others. All four of these charters boost student performance substantially (especially in math) compared to the low-performing urban schools that lottery losers attend. Because each of these charter schools targets disadvantaged areas, they also have a competitive advantage against surrounding traditional public schools. Because these charters are all trying to turn around the prospects of youth from disadvantaged neighborhoods, it is perhaps not surprising that they have adopted similar “No Excuses” strategies, which have been cited for decades by qualitative researchers as important for improving student performance, As noted earlier, these strategies include uniforms, high expectations from principals and teachers, a tightly enforced discipline code, along with intensive tutoring, longer instruction time, regular feedback, college preparation services, and an energetic commitment to ensuring the academic success of all students. Another feature of these schools are empowered, flexible, and inspiring principals, whose presence may be necessary to implement “No Excuses” schools successfully.

•There is some question about the extent to which the “No Excuses” framework captures what is different about these schools. While these schools share many similarities, they also exhibit distinct differences in curricula and culture—for example, KIPP schools follow a particularly unique setup, with middle schools starting in Grade 5 instead of 6, students receiving 'paychecks' for exhibiting good behavior that can be used for participation in school activities, and classrooms requiring students to ‘SLANT' (Sit up straight, Listen, Ask questions, Nod, and Track the person speaking with your eyes). At Harlem Children’s Zone’s 's Promise Academy, students receive a free daily breakfast and regular instruction on character and social emotional issues in gender-based groups, and all classrooms are equipped with smart boards. Suspension rates also differ. UP Academy and SEED report relatively high suspension rates (33.5 percent in 2013 for UP compared to a 2.8 percent state average, and 52 percent for SEED compared to a 23 percent city average), while KIPP Lynn and Harlem Children’s Zone's Promise Academy report low suspension rates that are close to state averages (4.7 and 2.5 percent, respectively).

•Moreover, some evidence suggests that these four charter schools may spend more per student than the traditional public schools, because they receive additional funding from charitable foundations. KIPP, for example states that 15 percent of its annual operation expenses is covered by philanthropic contributions.