all-statistics-are-local

What the Dashboard Didn’t Show You (Or, “The Denominator Moved”)

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Roosevelt Elementary started Year 1 of Elevate with 100 students. It ended the year with 400. The other two schools held roughly steady. The district grew from 600 students to 900, and the composition of that denominator shifted decisively toward the lowest-scoring school. That one fact explains the entire dashboard. Elevate worked. Every school’s average … Read more

Pick One from Three (All Three Numbers Are Correct)

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Last week’s post ended with a theorem. This one starts with a dashboard. The theorem — Arrow’s impossibility result, applied to the aggregation problem that Simpson’s paradox creates — is on the record in All Measurements Are Local if you want it. The short version: when subgroup results conflict with each other and with the … Read more