The Averaged AmericanAmericans today "know" that a majority of the population supports the death penalty, that half of all marriages end in divorce, and that four out of five prefer a particular brand of toothpaste. Through statistics like these, we feel that we understand our fellow citizens. But remarkably, such data now woven into our social fabric became common currency only in the last century. Sarah Igo tells the story, for the first time, of how opinion polls, man