Project Blue Book Special Report No. 14: Analysis of Reports of Unidentified Aerial Objects

Special Report No. 14 was issued by the U.S. Air Force's Air Technical Intelligence Center on 5 May 1955. It is a statistical study of about 4,000 reports of unidentified aerial objects from June 1947 to December 1952. The reports were reduced to IBM punched cards and analyzed with methods including chi square tests. The report concludes that the reports it examined are very unlikely to represent technology beyond present scientific knowledge, and it notes that no case produced valid physical evidence.

T A B L E X CHI SQUARE TEST OF REVISED KNOWNS VERSUS
UNKNOWNS ON THE BASIS OF SHAPE
Shape
Elliptical
Rocket or aircraft
Meteor or comet
Flame
T e a r d r o p , lenticular,
or .conical
Other
Not stated
Number of
KNOWNS
632
72
9
47
79
151
296
Adjusted
Number of
KNOWNS (K)
213
24
3
16
27
51
100
Number of
UNKNOWNS (n)
195
3 3
4V10.1.
22
54
116
X 2 ,
7jr_n\2
K
1. 52
3 . 3 7
I i~>
1. 5c
0 . 9 3
1.76
2. 56
f
Total 1286 434 434 11. 46
D e g r e e s of f r e e d o m
5%
1%
1 1 . 1
15. 1
72