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 XIII CHI SQUARE TEST OF REVISED KNOWNS VERSUS
UNKNOWNS ON THE BASIS OF LIGHT BRIGHTNESS
Light Brightness
Number of
KNOWNS
Adjusted X ,
Number of Number of (K-n)
KNOWNS (K) UNKNOWNS (n) K
Sunlight on mirror
Sunlight on aluminum
Sunlight on plaster,
stone, or soil
Brighter than moon
i • Like moon or duller
] than moon
] Not stated
*j Total
•i
i
24
136
63
143
4 2
878
1286
8
46
21
48
15
296
434
D e g r e e s of freedom
5%
1%
14
28
16
61
22
293
434
2.67
1. 19
3. 52
3. 27
0.03
10. 68
9 . 5
13.3
75