Abstract

In the search for patterns of the UFO phenomenon, the geographical distribution has shown contradictory results. After more than 40 years of studies, there is not yet a clear conclusion on whether the relationship between the number of reports and population density is direct or inverse. We have reviewed some of these works and found how to reconcile all of them. We found that there is a direct relationship between number of sightings and population density; however, the increase in number of reports is not proportional but sub-lineal respect to the increase of population.