Look Elsewhere Effect
The look-elsewhere effect (sometimes referred to as LEE) is a cognitive bias that occurs in the statistical analysis of scientific experiments, particularly in the study of complex particle physics. In this discipline, statistically significant results are sometimes derived by chance, simply because of the size of space being searched.
For instance, in astronomy a huge swath of space might be searched with the hope of a single comet being found. Because such a wide swath of space was searched, comets will most likely be spotted. But if the researchers had chosen a particular area in which to search the likelihood of a comet being found would be smaller. So because the area searched was so large it seems as if comets are more common than they actually are. This skews the perceived occurrence of comets -- it makes them seem more common than they actually are due to the huge space searched.