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.

Degrees of freedom
5%
1%
8
15. 5
20. 1
62
TABLE II
Color
CHI SQUARE TEST O|F KNOWNS VERSUS
UNKNOWNS ON THE BASIS OF COLOR
Number of
KNOWNS
Adjusted
Number of
KNQWNS (K)
Number of
UNKNOWNS (n)
White
Metallic
Not stated
Orange
Red
Yellow
Green
Blue
Other
405
313
209
172
146
128
130
67
195
Total 1765
100
77
51
42
36
31
32
17
48
434
112
76
62
49
33
31
14
26
31
434
(K-n)'
K
1.
0.
2.
1.
0.
10.
4.
6.
44
01
37
17
25
0
13
76
02
26. 15
, =