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 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