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 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
4 V10.1.
22
54
116
X2 ,
7jr_n\2
K
1. 52
3.37
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%
11.1
15. 1
72