It’s a phenomenon that occurs when a statistically significant observation is found but, actually, arose by chance and due to the size of the parameter space and sample observed. It usually happens in scientific experimentation and particularly in the field of physics, the look-elsewhere effect gained media attention in 2011 in the search for the Higgs boson. It tends to create an inflation of the data and “fake” its significance.
A commonly cited research to explain the look-elsewhere effect apart from the Higgs boson is the Swedish study that explored the potential health concerns of living near high-voltage powerlines in 1992. The study concluded that the children living the closest had four times more chance to suffer from leukaemia.The problem with the conclusion, however, was that they failed to compensate for the look-elsewhere effect; in any collection of 800 random samples, it is likely that at least one will be at least 3 standard deviations above the expected value, by chance alone