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.

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TABLE III
Number of
Objects P e r
Total
CHI SQUARE TEST OF KNOWNS VERSUS
UNKNOWNS ON THE BASIS OF NUMBER
Number of
Adjusted
Number of Number of
1765 434 434
X 2 ,
(K-n)2
Sighting
1
2
3-10
11 or more
Not stated
KNOWNS
1339
159
185
4 1
4 1
KNOWNS (K)
" 329
39
46
10
10
UNKNOWNS (n)
297
37 l
70
25
5
K
3. 11
0. 10
12. 52
22. 50
2. 50
40.73
D e g r e e s of f r e e d o m
5%
1%
9. 5
13. 3
63