Project Blue Book Special Report (second copy)

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.

TABLE IV CHI SQUARE TEST OF KNOWNS VERSUS
UNKNOWNS ON THE BASIS OF SHAPE
Total 1765 434 434
Shape
Elliptical
Rocket and aircraft
Meteor or comet
Teardrop, lenticular,
or conical
Flame
Other
Not stated
Number of
KNOWNS
838"
80
55
103
96
193
400
Adjusted
Number of
KNOWNS (K)
206
20
14
25
24
47
98
Number of
UNKNOWNS (n)
195"
33
4
22
10
54
116
X2,
(K-n)2
K
0. 59
8.45
7. 14
0.36
8. 17
1.04
3.30
29.05
D e g r e e s of f r e e d o m
5%
1%
12.6
16.8
64