According to a paper released by the National Bureau of Economic Research, first-year college students who are assigned roommates with video-game consoles study 40 minutes less per day, on average, than first-year students whose roommates did not bring consoles. And that reduction in study time has a sizable effect on grades: First-year students whose roommates brought video-game consoles earned grades that were 0.241 lower, on a 4-point scale, than did equivalent students whose roommates did not have consoles. The point of the paper is not to prove anything about video games. Instead, the researchers wanted to examine the relationship between the amount of time students spend studying and the grades they earn.