Gladwell discusses the K. Anders Ericsson study in chapter 2 of Outliers.

The study in question divided a class of violinists at the Berlin school of music into three groups based on their ability levels. Each student was then asked to calculate how many hours he or she had spent practicing since they first picked up the violin.

The study found that students in the top, elite group had practiced an average of 10,000 hours, steadily increasing the number of hours per week as they got older. The conductors of the study then conducted the same survey with piano players with similar results.

Gladwell infers from this study that people need to spend 10,000 hours on a specific skill before they can become masters of it. He also takes note of the fact that the study found no “naturals” or “grinds,” or people who were able to make it in the top tier on talent alone or hard workers who still fell short of their goals.

Therefore, Gladwell concludes that if someone is willing to put in the time required to master a desired skill, then he or she will reach the top of his or her field. In fact, he insinuates that this hard work is what makes a marginally talented person into an exceptional talent.