
Relationship Between Practice and Performance in Sports: A Meta-Analysis (2016) [pdf] - luu
https://artscimedia.case.edu/wp-content/uploads/sites/141/2016/09/14214856/Macnamara-Moreau-Hambrick-2016.pdf
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nopinsight
A good analogy is that expertise is like an area of a rectangle: Both innate
factors and practice contribute to it.

Which contributes more? It depends on the variance on each dimension. We see
from Fig 3 (page 9) in the paper that the unexplained variance is highest for
elite athletes at 99%. Why? Because almost all of them practice as much as it
is useful to do so. In other words, the heights of their rectangles are about
the same, almost all of their area differences depend on other factors [1].
For other groups, the variation in practice time explains more about their
performance differences.

[1] These may include innate talent, techniques, psychological factors, etc.
With more than two dimensions, we may need to change the analogy which I do
not have the time to get into now. Also, as with most analogies, it is not
perfect. Practice time is likely not independent of talent.

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mrchicity
Money quote on page 345: "In the second study, Mosing, Madison, Pedersen,
Kuja-Halkola, and Ullén (2014) had over 10,000 twins representing an
extremely wide range of music skill estimate deliberate practice and perform
tests of music aptitude. Mosing et al. (2014) found that there were genetic
effects on both music practice and music aptitude. More important, there was
no evidence for a causal influence of music practice on music aptitude.
Identical twins differing massively in amount of deliberate practice did not
differ significantly in music aptitude."

Apologies for being contrarian, but let me flip things around: Perhaps people
who are able to benefit from practice enjoy it and tend to do more of it.

I get excited learning about the latest C++17 features and used to love
reading stock exchange specifications, which most people would find about as
exciting as a root canal. I find it rewarding because I can apply what I
learned and feel a sense of satisfaction. Conversely, I've always sucked at
golf and could barely stomach the half-dozen lessons I tried, even though I
consider myself a diligent person and spent years practicing many other
things. I never improved my swing and the entire experience was nothing but
frustration. If you have a rough time at a beginner or intermediate level,
it's hard to gin up the desire for continued practice beating your head to a
wall.

The premise of this paper is naturally enticing. If you had only tried a bit
harder practicing lay ups in gym class, you could be just as good as Michael
Jordan (ok more like you could get a bit closer, since they claim practice
explains ~20% of results). I don't really buy it.

~~~
taneq
In the same vein, I think the term "deliberate practice" may produce
misleading results. If you love music and you're very good at it, you may not
count a jam session or some idle noodling around on a guitar to be "deliberate
practice" but they would still contribute to your skills.

Likewise I suspect if you asked a bunch of mid-level gamers how much time they
spent "deliberately practicing" to improve their skills, the answer would be
low compared to their total playtime, and that their skill levels would
correlate much more strongly with total playtime than with deliberate
practice.

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barry-cotter
Neither of your examples qualify as deliberate practice. People can plateau at
one skill level for decades and make sudden jumps in ability by deliberately
focusing on one specific skill. Expertise is at least in part, the combination
of excellence in multiple related skills.

> An expert breaks down the skills that are required to be expert and focuses
> on improving those skill chunks during practice or day-to-day activities,
> often paired with immediate coaching feedback. Another important feature of
> deliberate practice lies in continually practicing a skill at more
> challenging levels with the intention of mastering it.

K. Anders Ericsson, Ralf Th. Krampe, and Clemens Tesch-Romer. The Role of
Deliberate Practice in the Acquisition of Expert Performance. Psychological
Review 1993, Vol. 100. No. 3, 363-406 [

~~~
taneq
That's kind of the point. "Deliberate practice" definitely helps to hone
particular skills which fill holes in your overall competence. When you're
performing at ultra high levels, you probably already _have_ optimal
performance in most areas, and all you have left to practice are particular
skills.

Also, how you measure "sports performance" and what a percentage point means
at different levels seems crucial to the whole thing. Maybe deliberate
practice only accounts for 1% of performance... but an athlete who's 99%
perfect is twice as good as an athlete who's 98% perfect.

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joaorico
Anders Ericsson has replied to this meta-analysis [1], which in turn got a
reply from McNamara et al [2].

In Ericsson's opinion/definition [1], deliberate practice is "individualized
practice with training tasks (selected by a supervising teacher) with a clear
performance goal and immediate informative feedback was associated with marked
improvement"; and he argues "In contrast, Macnamara, Moreau, and Hambrick’s
(2016, this issue) main meta-analysis examines the use of the term deliberate
practice to refer to a much broader and less defined concept including
virtually any type of sport-specific activity, such as group activities,
watching games on television, and even play and competitions. Summing up every
hour of any type of practice during an individual’s career implies that the
impact of all types of practice activity on performance is equal—an assumption
that I show is inconsistent with the evidence."

McNamara et al reply saying that evidence only accounts for a relatively small
fraction of expert performance [2]: "we found that deliberate practice
accounted for a sizeable amount of variance in sports performance (18%), but
it left a much larger amount unexplained. Ericsson’s (2016, this issue)
evaluation of our research is undercut by contradictions, omissions, and
errors." They conclude that "The available evidence indicates that deliberate
practice, though undeniably important, does not largely account for individual
differences in expertise. Building on Ericsson’s pioneering work, the task now
is to develop theories of expertise that include multiple factors."

[1] Summing up hours of any type of practice versus identifying optimal
practice activities: Commentary on Macnamara, Moreau, & Hambrick (2016)
[http://journals.sagepub.com/doi/abs/10.1177/1745691616635600](http://journals.sagepub.com/doi/abs/10.1177/1745691616635600)

[2] How Important Is Deliberate Practice? Reply to Ericsson (2016)
[http://journals.sagepub.com/doi/abs/10.1177/1745691616635614](http://journals.sagepub.com/doi/abs/10.1177/1745691616635614)

~~~
_ttg
Seems like I need an account to either purchase or rent both articles?

~~~
cristoperb
[http://sci-hub.tw/10.1177/1745691616635600](http://sci-
hub.tw/10.1177/1745691616635600)

[http://sci-hub.tw/10.1177/1745691616635614](http://sci-
hub.tw/10.1177/1745691616635614)

~~~
_ttg
thanks!

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sudofail
This was a pretty interesting read, and something I've often wondered about. I
remember when LeBron James joined the NBA. It just baffled me at the time how
some 18 year old high schooler could be so much better than professional
players, players who've played day in and day out for _years_. Hours of
deliberate practice didn't seem to be an adequate explanation.

~~~
wallflower
LeBron James' greatest gift is his brain that has a phenomenal photographic
memory.

> In the jovial postgame locker room, it's pointed out to James by a reporter
> that almost exactly five years earlier, he'd won a game with a jumper at
> Oracle Arena at the buzzer from virtually the same exact spot at the same
> basket.

"Not really," James says in response. "That one was probably about six feet
closer to the baseline and inside the 3-point arc. It was over Ronny Turiaf, I
stepped back on him but I crossed him over first and got him on his heels. I'm
sure of it. It was down the sideline a few feet. It was a side out-of-bounds
play; this one we brought up."

[http://www.espn.com/nba/story/_/id/11067098/lebron-james-
gre...](http://www.espn.com/nba/story/_/id/11067098/lebron-james-greatest-
weapon-brain)

~~~
pitt1980
no

his greatest gift is that he's 6'8

[https://investing.calsci.com/statistics.html](https://investing.calsci.com/statistics.html)

he has a collection of many traits that make him a unique talent

of all those traits, the one with the largest standard deviation from the norm
is almost certainly his height

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markc
No, largest standard deviation doesn't make it his greatest gift unless its
_weighted_ contribution to his overall skill (some combination of importance
and rarity) was the greatest. There are certainly positive traits even rarer
than height that have little or no bearing on skill, not to mention that
_optimum_ is not the same as _maximum_ for some traits, probably including
height.

~~~
pitt1980
fair,

are you arguing that of all the traits under consideration, height isn't one
of ones of primary importance for his success on the basketball court?

ie, if we keep all his various traits constant, and one by one, move each of
them back a standard deviation

is there a trait that would change his effectiveness more than moving his
height back a standard deviation?

~~~
markc
No, undoubtedly optimum height is a major factor in his and other basketball
players' success, and I don't know of any other factor that _obviously_
dominates it.

His mental talents _may_ be even rarer however. I don't know how we could
know.

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sytelus
TLDR;

The 10,000 hr practice myth has long been busted by series of studies and this
meta study is another one in the series focusing on sport. It turns out that
among non-elites, only 18% of performance difference can be attributed to
deliberate practice! More surprisingly, there are significant non-elites who
spend same or more hours in deliberate practice which means that simply
looking at this number doesn't allow you to accurately distinguish between
elites and non-elites. Finally, starting at childhood has minimal advantage in
performance difference.

This is another big stab in the nature vs nurture debate. There are many
studies (also cited in this paper) which has indicated that deliberate
practice only account for 30% of performance difference in activities like
chess requiring purely cognitive abilities. So for physical activities, it
makes even less difference! The paper has extensive references at the end
which indicates that rest of the majority of differences comes from genetics
and possibly psychological factors such as confidence, sensitivity to rewards,
ability to focus, performance anxiety and so on.

So currently, it looks to me nurture contributes 1/3 and potentially (this is
not in paper) nature another 1/3 and psychological factors another 1/3.

