This chapter had four big lessons. Each of the following situations illustrates one and (we think) only one of those lessons. Which one?

a. Militaries throughout the world give medals, citations, and other public honors to members of the military who excel in their duties.

b. People tip for good service after their meal is concluded.

c. Real estate agents work on commission, but office managers at a real estate office are paid a straight salary.

d. In Pennsylvania in 2009, two judges received $2.6 million in bribes from a juvenile prison. The more people they sent to jail, the more they received from the prison owners.

What tipped off prosecutors was that the judges were sentencing teens to such harsh sentences for relatively minor crimes. One teenager was sent to prison for putting up a Facebook page that said mean things about her school principal; another accidentally bought a stolen bicycle. (Both judges pled guilty.)

e. Studies have shown that when employers initially enroll all workers in a retirement plan, the workers save more than when they must ask to join the retirement plan, even when in both cases workers can quit or join the plan at any time.