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But the control group was families who did opt in and who lost the lottery.

• cma 1y ago
  Still the ones who got in would be with more other students who opted in, the ones who didn't get in would be with more students who didn't opt-in to the lottery. You would need to have a second group of those who lost the lottery and were all put into the same non-Montessori school with no others who didn't opt-in maybe.
  • rahimnathwani 1y ago
    Oh you mean it could all be peer group effects?
    • cma 1y ago
      Yeah but even then teachers that opt in to train in Montessori might just be better teachers, and converting a whole school system to Montessori, training everyone, might not have as good results.