1955 · Battelle Memorial Institute statistical analysis
Project Blue Book Special Report 14, released in 1955, is a seminal statistical analysis of 3,201 UFO sightings reported between 1947 and 1952. Conducted by the Battelle Memorial Institute for the U.S. Air Force, it utilized chi-square tests to compare 'unknown' cases against 'known' cases. The report concluded that the statistical distributions of unknown cases differed significantly from known cases, suggesting that unknowns were not simply misidentified conventional objects, with 21.5% of cases remaining unidentified after investigation.