Documents / Report
This is Project Blue Book Special Report No. 14, "Analysis of Reports of Unidentified Aerial Objects," Project No. 10073, dated 5 May 1955. The study reduced about 4,000 sighting reports received by the U.S. Air Force between June 1947 and December 1952 to IBM punched cards and analyzed them statistically, including chi square tests comparing knowns with unknowns. It concludes that the reports very probably do not represent technological developments beyond present scientific knowledge, and it notes that no case produced physical evidence.
“Works”18 pages
% (4) Duration of observation Here there is an excess of KNOWNS in the less-than- 5-second group. Again, the majority of KNOWNS in this group are astronomical. The greater proportion of UNKNOWNS in the 31- to 60-second and 61-second to 5-minute groups cannot be explained. (5) Speed The major contribution to chi square for this char- acteristic is due to a large excess of UNKNOWNS in the over 400-mph class. It can be assumed that^ some of the excessive speeds are inaccuracies in estimates by observers. However, some radar sightings, which are practically impossible to identify, show objects with speeds of 1, 000 to 2, 000 mph and over, and these reports account for a number of these UNKNOWNS. (6) Light brightness , . Since this chi square was not significant, it is not necessary to discuss it here. \ An examination of these\discrepancies thus brings up a very interest- ing point. In every case for which there is a significant excess of KNOWNS over UNKNOWNS, the excess can be attributed to an excess of identifiable astronomical phenomena. This would seem to lead to the conclusion that astronomical phenomena are easy to identify and there are very few left in the UNKNOWNS. Accordingly, the astronomical object sightings were deleted from the KNOWN object sightings and the Chi Square Test was again applied. The results are shown in Tables VIII through XIII, where in this case the KNOWNS do not contain astronomical sightings. It will be noted that some groups were combined when the adjusted number of KNOWNS was ten or less, except for the case for which the number of objects per sighting was the characteristic studied. These were borderline cases, and no good combination of groups existed. It is apparent that the deletion of astronomical sightings gives a better fit, although the decision is not clear cut, since for two cases (light bright- ness and speed), the chi square increased. However, it can again be pointed out that the reporting of these two characteristics is highly subjective and is open to question. The estimation of speed is especially open to question because of the impossibility of accurately determining it visually. 69
Report, cited by the archive. The PDF is mirrored here; the original link is under it. 309 pages are in the text index: search them above, or from the library's search.