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 XI CHI SQUARE TEST OF REVISED KNOWNS VERSUS UNKNOWNS
ON THE BASIS OF DURATION OF OBSERVATION
Duration of
Observation
Number of
KNOWNS
Adjusted
Number of
KNOWNS (K)
Number of
UNKNOWNS (n)
X 2 ,
K
0.
1.
1.
3.
2.
2.
1.
0.
52
56
2 3
90
31
9 4
16
72
5 sec or less
6-10 sec
11.-30 sec
31-60 sec
61 sec-5 min
6 min-30 min
Over 30 min
Not stated
92
47
118
92
252
259
91
335
Total 1286
31
16
40
31
85
87
31
113
434
27
21
33
42
99
71
37
104
434 14. 34
Degrees of freedom
5%
1%
14. 1
18. 5
73
gfc :-•