To prove that matter waves exist as per the predictions of the theory of relativity physicists could use a telescope to detect signals and verify. De Broglie could perform young's double-slit experiment to verify that light is indeed a particle and a wave. While such natural experiments with absolute power to confirm or to reject theories have been the norm in physics social scientists could only dream about something that would be remotely close to this. This year Nobel prize in economics has been awarded to devise robust statistical techniques that allow economists to make causal inferences from natural events.