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 VI CHI SQUARE TEST OF KNOWNS VERSUS
UNKNOWNS ON THE BASIS OF SPEED
Speed
Number of
KNOWNS
Adjusted
Number of
KNOWNS (K)
Number of (K-n)Z
UNKNOWNS (n) K
Stationary
L e s s than 100 mph
100 to 400 mph
Over 400 mph
Meteor-like
Not stated
249
154
181
403'"
8 3
695
61
38
4 5
99
20
171
Total 1765 434
53
26
58
145 "
16
136
434
1.05
3.79
3.76
21.37
0.80
7. 16
37. 93
Degrees of freedom
5%
1%
11.1
15. 1
66