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The "Debunking" of Hart & Risley and How We Use Science
The recent kerfuffle concerning Hart & Risley (1995) and the 30 million word gap offers an object lesson in science, the interpretation of science, and the relation of science and policy.
Let’s start with the new science. Douglas Sperry and colleagues sought to replicate Hart & Risley, who reported the 30 million word gap—that’s the projected difference in total number of words directed to a child by caregivers when comparing children of parents on public assistance and children of parents in professional positions. Sperry and his team claim not to find a statistically reliable difference among parents of different social classes.
Twitter was quick to pounce: