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.

TABLE VII CHI SQUARE TEST OF KNOWNS VERSUS UNKNOWNS
ON THE BASIS OF LIGHT BRIGHTNESS
Light Brightness
Number of
KNOWNS
Adjusted
Number of Number of
KNOWNS (K) UNKNOWNS (n)
Sunlight on mirror
Sunlight on aluminum
Sunlight on plaster,
stone, or soil
Brighter than moon
Like moon or duller
than moon
Not stated
Total
47
151
76
27 3-
68
-
1150
1765
11
37
19
67
17
283
434
14
28
16
61
22
293
434
X
(K-
K
0.
2.
0.
0.
1.
0.
5.
2
»n ) 2
82
19
4 7
55
4 7
3 5
8 5
Degrees of freedom
5% 11. 1
15. 1
67