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 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