Outliers: The Story of Success · chapter 2 · id outliers-c2-01-10000-hours-of-practice-is-the

“10,000 hours of practice is the magic number for achieving world-class expertise in any field -- a universal threshold supported by research on violinists, pianists, chess players, and athletes.”

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Ericsson, Krampe & Tesch-Romer (1993), Psychological Review 100(3)DOI registry: valid

The 'best' violinists at the Music Academy of West Berlin averaged 10,000 hours of deliberate practice by age 20. The 'good' group averaged 7,800 hours. Music education students averaged 4,600 hours.

Macnamara, Hambrick & Oswald (2014), Psychological Science 25(8) -- meta-analysis of 88 studies, N=11,135DOI registry: valid

Deliberate practice accounted for only 12% of the variance in performance overall. By domain: Games 26%, Music 21%, Sports 18%, Education 4%, Professions <1%.

Ericsson & Pool (2016), Peak: Secrets from the New Science of Expertise, Houghton Mifflin Harcourtsource alive

There is no magic number. Gladwell turned an average into a universal rule. The 10,000 hours was the mean for the best violin group at age 20 -- not a minimum, threshold, or guarantee. Not all practice is equal.

Campitelli & Gobet (2011), Current Directions in Psychological Science 20(5)DOI registry: valid

The range of hours to reach chess master level varied from 3,016 to 23,608 hours -- an 8x spread. Some players reached master with ~3,000 hours; others never reached it despite 25,000+ hours.

Mosing, Madison, Pedersen, Kuja-Halkola & Ullen (2014), Psychological Science 25(9) -- twin study, N=10,500DOI registry: valid

In 10,500 Swedish twins, the twin who practiced music more did NOT show significantly better music ability. Genetic factors explained a large proportion of both the propensity to practice and the level of ability achieved.

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