I haven't had a chance to dig out the original paper but I will try to.
Something I don't think most who quote the study bother to do. The test was deliberately designed to make it as difficult as possible, to best test techniques for VFR pilots in IMC.
The aircraft was a Bonanza, loaded to MTOW at the aft CG limit.
EQUIPMENT IN THE AIRPLANE
In the experiment it was decided to use only those instruments and
equipment specified in Civil Air Regulation 43.30 for visual flight rules,
plus a turn indicator. Therefore in equipping a standard Beechcraft C-35
for these case studies, the artificial horizon, the directional gyro, and the
rate-of-climb indicators were covered
BASIS OF SELECTION
The bases of selection for the volunteer case study subjects were that
they should ( 1 ) be representative as to chronological age — the group
selected ranged in age from 19 to 60 years, (2) have had no previous
instrument experience under either simulated or actual conditions,
(3) have had a minimum of experience in the Beechcraft Bonanza
None of the students had soloed a Bonanza.
It is an interesting study, but I don't think you can conclude much about how long VFR pilots last in IMC in a real situation.
Certainly they sometimes crash, but what percentage of incidents we don't know.
What looks like a bad OCR version of the study is here:
https://archive.org/stream/180degree...1brya_djvu.txt