10,000 Hours +/- 10,000 Hours

Dated Apr 29, 2014; last modified on Sat, 06 Nov 2021

10,000 Hours, YMMV

10,000 hours has been lauded by popular authors, e.g. Malcolm Gladwel’s Outliers, and Geoff Colvin’s Talent is Overrated. Notably, Ericsson has dismissed the “10,000 hours rule” as misconstruing his positions: genetics play a role; 10,000-hours of deliberate practice is not all that counts.

Most data in support of the 10,000-hours rule has been cross-sectional and retrospective.

A cross-sectional study is a type of observational study that analyzes data from a population (or a representative subset) at a specific point in time.

Average time to chess master level was ~11,000 hours. However, the range was 3,000 hours to 23,000 hours.

The study was notable for tracking Elo ratings over time, as opposed to retrospectives.

The Mathew Effect

Stephan Holm put in 20 years of deliberate practice for the high jump, while Donald Thomas had a year of deliberate practice after coming from basketball. However, both achieved similar olympic success. One possible explanation is Thomas’s longer Achilles tendon. While exercise can increase tendon stiffness, genetics also play a role.

To distinguish nature and nurture, give people the same amount of practice and see whether they become more or less alike in performance. While there was across-the-board improvement, larger individual differences increase with equal training.


  1. Training History, Deliberate Practice and Elite Sports Performance: An analysis in response to Tucker and Collins review - what makes champions? Ericsson, K. Anders. British Journal of Sports Medicine. scottbarrykaufman.com . dx.doi.org . 2013.
  2. The Role of Domain-Specific Practice, Handedness, and Starting Age in Chess. Gobet, Fernand; Guillermo Campitelli. Developmental Psychology. bura.brunel.ac.uk . 2007.
  3. The Effect of Practice in the Case of a Purely Intellectual Function. Thorndike, Edward L. American Journal of Psychology. 1908.