" Of all the things that we think matter to SAT scores, the number of test takers in the room is never one of them. What do you normally think is most predictive of SAT scores? Scores at the school over the past decade? The amount of federal funding received? The percentage of minority students? Socioeconomic class? Nope. The N, or number of test takers. Amazingly, the researchers found a –0.68 correlation between the N of test takers per location and their SAT score, meaning that the more test takers in the room, the lower their SAT scores. And that is a huge effect. A correlation of –1.0 would mean that test takers’ entire SAT score was determined solely by the number of people in the room and that none of it was based upon their intelligence and education. A –0.68 correlation is massive. "

― Shawn Achor , Before Happiness: How Creating a Positive Reality First Amplifies Your Levels of Happiness and Success