Beyond the anomalies (and earlier than them in its emergence) lay another kind of problem for efficient-market theory a problem that seems technical but is deep in its ramifications. If changes in security prices were in some sense "random," how was that randomness to be characterized mathematically? Was it a "mild" randomness that could be treated by standard statistical techniques, or a "wild" randomness not susceptible to those techniques?

Donald MacKenzie, An Engine, Not a Camera, loc. 463