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NBER posted an RCT of Bridge private schools in Kenya that’s gotten attention for the big impacts on student achievement. Quick take: Promising findings but not definitive due to key study limitations (especially in methods of testing achievement).


  • Per the study: Bridge schools "employ a highly-standardized approach to education...deliver highly detailed lesson guides to teachers...also standardize systems for daily teacher monitoring and feedback, school construction, and financial management."

Study Design & Findings:

  • The RCT had a sample of 5,300 primary students in grades 1-8 and 4,400 pre-primary students age 3-5.

  • At the 2 year follow-up, the study found sizable effects on achievement for both the primary students (intent-to-treat effects of about 0.3-0.4 standard deviations) and pre-primary students (intent-to-treat effects of about 0.5-0.6).


  • A study limitation is that achievement was measured with tests designed specifically for the study (i.e., not standardized tests) - which can overstate impacts. A standardized test given to many of the older students found much smaller impacts (about 0.10).

  • Also in grades 3 & below, the tests were given via 1-on-1 interviews (rather than paper+pencil), and there's no indication testers were blinded as to which students were treatment vs control. So tester bias (conscious or unconscious) - e.g., as Bridge supporters - might affect their scoring.

  • Finally, the study found no discernible effect on the percent of older primary students going on to secondary school (71% C vs 72% T, not statistically significant).


  • Overall, I think findings are promising but not yet definitive; hopefully future RCTs will address above issues.

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