Qm
Statistics

New teaching method in one class: diff-in-diff

difference-in-differencescausal-inferenceeducation

A teacher tries a new method in Class A and keeps Class B on the usual method as a control. Average test scores before and after:

  • Class A (treated): 60 before, 75 after.
  • Class B (control): 62 before, 70 after.

Compute the difference-in-differences estimate of the new method's effect, and explain why it is smaller than the raw 15-point gain.

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