Complex sentence: A scientific and statistical analysis of 3200 Air Force cases by the Battelle Memorial Institute from 1952 to 1954 found that most were indeed due to natural phenomena, about 2% were due to hoaxes or psychological effects and only 0.4% were thought due to clouds.
Split into simpler sentences: A scientific and statistical analysis of 3200 Air Force cases by the Battelle Memorial Institute from 1952 to 1954 found that most were indeed due to natural phenomena. But only about 2% were due to hoaxes or psychological effects and only.4% were thought due to clouds.