Before the presidential election, many Democrats were puzzled by the seeming disconnect between “economic reality” as reflected in various government statistics and the public’s perceptions of the economy on the ground. Many in Washington bristled at the public’s failure to register how strong the economy really was. They charged that right-wing echo chambers were conning voters into believing entirely preposterous narratives about America’s decline. What they rarely considered was whether something else might be responsible for the disconnect — whether, for instance, government statistics were fundamentally flawed. What if the numbers supporting the case for broad-based prosperity were themselves misrepresentations?...