Over their lives, people try to spread their spending more evenly than their income. The permanent income hypothesis, developed by Milton Friedman, says that a person’s spending decisions are guided by what they think over their lifetime will be their average (also known as permanent) income. A sharp increase in short-term income will not result in an equally sharp increase in short-term consumption. What if somebody unexpectedly comes into money, say by winning the lottery? The permanent income hypothesis suggests that people will save most of any such windfall gains. Reality may be somewhat different. (See life-cycle hypothesis. )