The ten-thousand-hour study was redone with thirty-nine violinists under double-blind conditions, and the group rated merely good had logged more practice hours than the group rated best — the original paper’s number was one average among several, never the threshold it became

The “10,000-hour rule” is one of the most repeated ideas in popular writing about skill and success: put in 10,000 hours of practice, the story goes, and elite performance follows. It comes from Malcolm Gladwell’s 2008 book Outliers, which drew on a 1993 study of violin students by psychologist K. Anders Ericsson and colleagues. The trouble, often overlooked in the retelling, is that “10,000 hours” was never the study’s own number. Ericsson’s team reported that the most accomplished violinists in their sample had, by age 20, accumulated an average of around 10,000 hours across a life of practice, one figure among several reported for different subgroups, not a threshold the researchers claimed to have discovered.

A 2019 study went further than pointing out that framing problem. It redid the underlying comparison, and found that practice hours didn’t cleanly separate the best violinists from the merely good ones at all.

The redo, and what it changed

The study, by Brooke Macnamara of Case Western Reserve University and Megha Maitra, published in Royal Society Open Science in 2019, recruited 39 violinists and split them into three skill groups of 13 based on teacher and expert assessments: best, good, and least accomplished. Crucially, the people doing the skill ratings did not know how many hours each violinist had logged, a double-blind design the original 1993 study didn’t use.

The result ran against the popular version of the rule. The “good” group had logged an average of 9,844 hours of deliberate practice; the “best” group averaged 8,224 hours, a difference that was not statistically significant (p = 0.364). The group rated merely good had practised more than the group rated best, not less.

That inversion sits against the original 1993 figures, where the reported averages for expert, good and less accomplished violinists were roughly 7,410, 5,301 and 3,420 hours respectively, a pattern that did track with skill level in that dataset. Macnamara and Maitra’s replication, using a comparable design decades later, did not reproduce that clean gradient.

Study findings & limitations

Deliberate practice wasn’t irrelevant in the 2019 data. It explained a portion of the variation in skill across the whole sample, alongside other factors the researchers didn’t fully identify. What it didn’t do was reliably distinguish the best performers from the good ones once a double-blind rating removed the possibility that raters were influenced, even unconsciously, by knowing who had practised more.

This is one study, with a modest sample of 39 people playing one instrument, not a verdict on how skill develops across every field. The authors are explicit that their finding complicates the strong version of the deliberate-practice account rather than replacing it with an equally strong alternative. What separated the best violinists from the good ones in this sample remains an open question the study doesn’t answer.

Why the strong version of the rule stuck

Gladwell’s framing had an obvious appeal: it turned talent into something within anyone’s control, a number to hit rather than a trait to be born with. That’s a more motivating story than “some mix of practice, teaching quality, feedback and factors nobody has fully mapped yet determines expertise,” even if the second version is closer to what the research, taken as a whole, actually supports.

The 1993 Ericsson study also became a launching point for later work suggesting that deliberate practice explains only a modest share of skill variation in many domains, with wide ranges depending on the field, larger in some structured activities like chess and classical music, smaller in domains like education or entrepreneurship where the path to expertise is harder to standardise and measure. Macnamara and Maitra’s violin data sits inside that broader pattern rather than overturning it entirely; it sharpens the question of what else is doing the work practice alone doesn’t explain.

What’s left of the idea

Practice still matters. Nothing in this replication argues that skipping it is a viable path to expertise, or that the violinists in the “least accomplished” group, who practised least of the three, would have caught up without practising at all. What the 2019 result challenges is narrower and more specific: the claim that hours logged, on their own, reliably sort good performers from great ones, and the idea that a single number, 10,000 or otherwise, functions as a threshold anyone can cross into elite performance.

The number that made the rule famous was a rounding of an average from one subgroup in one 1993 study. The rule that made the number famous doesn’t survive a closer look at the violinists it was built on.