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.

ro
c
O
100-
90-
80"
70-
60-
50"
40-
3 0-
20-
10-
0.
Not
stated
24.9%
0ver30mir
7.8 %
6-30 mi n
17.1 %
61 sec-
5min
16.7%
31-60 sec
6.8 %
11-3.0 sec
8.5 %
b-TO sec
5. I %
5 sec or
less
13.0%
oAstronomical> II
Aircraft
| |
y//////
Balloon^
'//////A
Insuf. info. cO f h p r/V L Unknown
Duration
0 20 30 40 50 60 70
Evaluations in Per Cent
90 100
FIGURE 13 DISTRIBUTION OF OBJECT SIGHTINGS BY DURATION OF SIGHTING WITH EVALUATION
DISTRIBUTION FOR EACH DURATION GROUP , A-7491