Similar to a Bellwether, a John Ringer refers to a leading indicator of some sort of change, similar to "canary in a coal mine". Unknown origin, has been used as a common phrase in corporate conference call settings at least going back to the late 90's.
As you can see here on this chart, the strong sales numbersact as a great John Ringer indicating healthy growth.
American economist from the University of Chicago. Known for his laughable lack of knowledge on economics, racistblog where he censors comments while claiming to oppose censorship, and complete lack of understanding on fiscal policy, which he often writes embarrassing articles on.