The Black Swan: The Impact of the Highly Improbable · chapter 2 · id the-black-swan-c2-06-galtons-original-1886-study-of
“Galton's original 1886 study of hereditary stature found that children's heights regress toward the population mean -- tall parents tend to have children shorter than themselves, and short parents tend to have taller children, with a regression ratio of approximately 2/3.”
VERIFIEDconfidence: high⚠ extracted by pipeline, re-audit pending
Receipts
Galton (1886), 'Regression Towards Mediocrity in Hereditary Stature', Journal of the Anthropological Institutesource alive
The offspring did not tend to resemble their parents in size, but always to be more mediocre than they. The slope of the regression line was 2/3, which Galton called the 'Ratio of Filial Regression.'
Senn (2011), 'Francis Galton and Regression to the Mean', Significancepaywalled · manual check queued
Galton's data consisted of 928 adult children and 205 parentages. He found the regression coefficient to be about 2/3, meaning children's heights deviated from the mean by only two-thirds of their parents' deviation.
Han, Ma & Zhu (2015), 'Galton's Family Heights Data Revisited', arXivpaywalled · manual check queued
Reanalysis of Galton's original data confirms the regression coefficient of approximately 0.67, consistent with Galton's reported 2/3 ratio.
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