Phenomenon: “Two of Mr. Price’s most valued employees quit, spurred in part by their view that it was unfair to double the pay of some new hires while the longest-serving staff members got small or no raises.”

Explanation: “A study by researchers at the University of Warwick and Cardiff University has found that money only makes people happier if it improves their social rank. The researchers found that simply being highly paid wasn’t enough — to be happy, people must perceive themselves as being more highly paid than their friends and work colleagues.”