I teach intro to business statistics usually every semester. While students grasp the concept of the mean rather easily, the notion of variance and standard deviation often takes a little longer.
Take the 10,000 hours "rule," for example.
Popularized in Malcolm Gladwell's "Outliers," the 10,000 hours rule basically states that through dedicated practice, reaching this "magic number of greatness" allows one to achieve a professional level of proficiency regardless of talent or skill.
In the fascinating new book, "The Sports Gene," David Epstein (that will likely provide a number of posts to fulfill my #8ManRotation quota), challenges the belief in 10,000 hours.
What is often ignored in the discussion are a couple of items. First, is the notion of sampling and research design. In the original 10,000 hours study of musicians, most individuals were already screened out, making it difficult to discover evidence of innate talent. It is extremely hard to create a longitudinal study where groups are divided into those who receive 10,000 hours of training against those who do not.
Second, variability is not often discussed. Is 10,000 the hard rule, or do some take a longer or shorter time. In the Sports Gene, Epstein highlights the work of Guillermo Campitelli and Fernand Gobet who recruited 104 competitive chess players of varying skill for a study of chess expertise. They found that it took 11,053 hours to make it as a professional chess player. Much more interesting was the range of hours it took to attain master status. "One player in the study reached master level in just 3,000 hours of practice, while another player needed 23,000 hours." As a result, Epstein notes about the musician study, "it is impossible to tell whether any individual in the study actually became an elite violinist in 10,000 hours, or whether that was just an average of disparate individual differences."
Epstein also shares an anecdote about the skilled Swedish high jumper Stefan Holm. Holm fastidiously practiced - 12 hours a day for years on end - to become a world class athlete, winning the Olympic gold medal in 2004 and equaling the record for the highest high-jump differential between the bar and the jumper's own height. However, in 2007, he faced Donald Thomas, a jumper from the Bahamas who had only just begun high jumping. In less than 8 months of training, Thomas cleared 7'7.75" to win the NCAA indoor high jump championship. Despite such insignificant training time, Thomas defeated Holm, winning the world championship. While not the sole reason, it was found that Thomas had an incredibly long Achilles tendon that better serves one's ability to rocket throught he air.
Nonetheless, being fat, 45 years old, and 5'9'' with a limited vertical leap, LeBron has nothing to worry about, even if I practice 10,000 hours or more. Much like Thomas had an incredibly long tendon, you can't teach height!