Air Force Project Blue Book Special Report 14 (Hynek's annotated copy)

Group 5 - Night sightings for which the sun was more than $ 1 0^{\circ} $ below the horizon and which were not included in Group 4.

Group 6 - Sunrise sightings for which the sun was between $ 0^{\circ} $ and $ 1 0^{\circ} $ below the horizon.

Group 7 - Sunrise sightings for which the sun was between $ 0^{\circ} $ and $ 1 0^{\circ} $ above the horizon.

These group numbers were punched on the cards and incorporated into the coding system. The number of OBJECT SIGHTINGS in each group for each identification was then tabulated and is given in Table I.

TABLE I OBJECT SIGHTINGS

	Angle of Elevation Group
Identification	1	2	3	4	5	6	7
Balloon	156	17	28	83	40	0	2
Astronomical	52	6	43	236	118	9	6
Aircraft	187	23	49	144	60	5	2
Light phenomena	8	2	4	25	7	0	0
Insufficient information	72	12	26	76	28	2	0
UNKNOWN	134	14	25	150	86	6	7
Other	64	8	12	50	36	3	7
Total	673	82	187	764	375	25	24

According to this table, a large majority of the KNOWN OBJECT SIGHTINGS in Group 1 (343 out of 467) were either aircraft or balloons. In Groups 4 and 5 combined, a large majority (681 out of 899) were either balloons, aircraft, or astronomical. Accordingly, a re-evaluation of the UNKNOWNS in these three groups was planned with the objective of determining which of the UNKNOWNS in Group 1 might possibly be aircraft or balloons and which of the UNKNOWNS in Groups 4 and 5 might possibly be balloons, aircraft, or astronomical objects. More will be said of this project later.

## Statistical Chi Square Test

In the meantime, mirror graphs had been constructed from the frequency tabulations which seemed to show that, when the KNOWNS (total less UNKNOWNS) and the UNKNOWNS were grouped according to one of six characteristics, the percentage of KNOWNS and the percentage of