The number comes from a study of 1,065 athletes from 43 teams from 19 organizations, including the United States Chess Federation and the World Chess Association. Their results showed a “significant effect of skillshare on chess skill, with a 1-year skillshare reduction of 0.17-to-0.47 standard deviations [standard deviations] on chess skill.” That means a player whose skillshare was 0.6 is about 1-point weaker. The study found that most of the effect was due to improvements in skills, including improving the chess-related skills such as analyzing, judging, and solving logic puzzles. These are the kinds of skills that can be bought easily through chess tournaments, and are usually the most expensive items in a player’s bags, because chess players spend so much of their time on them and to pay for them. The most important finding, the study’s authors said, is that most of the effect was due to improvement in the kinds of skills most important to chess, even if the impact in one area was small. “In all, we found a significantly larger effect of skillshare on chess skill,” the authors wrote. “The most significant finding was that, in general, skillshare had significantly larger effect, if we included the effects measured by chess skills measured in the same years, than measured by skillshare in the following three years.” (These three years of data include those from the 1999 and 2000 World Cup tournaments, and they are used in the study just for comparison.) A second study from 2011 looks at two other types of skill shares, one for each year (2000 and 2009) of the study. The first study showed that the effect of skillshare on chess performance is larger than on the performance itself: the skillshare that was associated with a 1-point improvement on the first year of the study had about a 0.25-point increase over the follow-up.
“From the point of view of the players, it seems to us to be a significant positive effect,” said David Molnar, the study’s deputy director and one of the study’s authors. Molnar is a chess-world-famous expert and consultant who is the president of the American Institute of Chess (also called the Chess Alliance), a chess association that promotes the game. (He received a prize from the alliance in 2002 for his work leading his professional career.) “The players themselves seem to say that the effect is real enough, even though it’s small,” Molnar said.