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@vkoganpolisci @dylanwiliam Self-made instruments align with the intervention, may include test items that control group students cannot answer (they did not learn that content ). And standardized, independent tests also measure what should be learned in a grade but what was not part of the intervention.

@dylanwiliam Why is the effect on researcher created measures of student achievement 4x larger?

A review of studies of teacher professional development on reading comprehension finds a 0.95 sd impact on teacher knowledge/practice, and a 0.19 sd impact on student achievement—the former being 5 times the latter coheres with teacher quality research: bit.ly/3xx09VH