Organized labor hasn’t had this much public support in 50 years, and yet the percentage of Americans in a union is near a record low. A.F.L-C.I.O. president Liz Shuler tries to explain this gap — and persuade Stephen Dubner that “the folks who brought you the weekend” still have the leverage to fix a broken economy.

In a new book called The Voltage Effect, the economist John List — who has already revolutionized how his profession does research — is trying to start a scaling revolution. In this installment of the Freakonomics Radio Book Club, List teaches us how to avoid false positives, how to know whether a given success is due to the chef or the ingredients, and how to practice “optimal quitting.”