Neil Charness, Michael Tuffiash, Ralf Krampe, Eyal Reingold and Ekaterina Vasyukova
In this study try to stablish which of the following three activities: studying alone, tournament practice (competitive play) and formal instruction is a stronger predictor of chess expertise.
After couple of surveys were conducted over a 375 chess players group from different countries, they found out that hours devoted to chess study alone were the strongest predictor of chess success.