10,000 hours not scientific, but also not false.

"10,000 hours of practice are required to achieve world-class performance in anything."

This false idea was popularized by Malcolm Gladwell in "Outliers." The scientist whose work it's based on (Anders Ericsson) has explained it's a misinterpretation of his work. What's true?

Ericsson explains: there's nothing special about 10,000 hours. Gladwell could have mentioned the amount of time the best violin students practiced by the time they're 18...7400 hours...Pianists who win international competitions tend to do so around age 30 with 22,000 hours.

Much to Gladwell's credit, he eventually admitted he was wrong (after having his view criticized): "This is David Epstein. He devoted several pages (of his book) to attack my work and I read the attack and realized that actually he was correct, so we became friends."

A meta-analysis on the link between the number of hours of deliberate practice and sports performance found a correlation of 0.43. That's not nothing, but it leaves a lot unexplained. Intriguingly, among just elite athletes, practice hours explain almost none of the variance!

But there's a kernel of truth in the 10,000-hour "rule." A large amount of practice (where reliable, rapid feedback is received, whether from a coach or just from self-observation of mistakes) is absolutely essential for developing expertise in most fields.