Records of wrong data can be as important as the correct figures. For example the LW made decisions based on their incorrect estimates of RAF strength and losses during the BoB. Leigh Mallory also believed in the effect of his big wing based on incorrect claims
The entire early British bomber offensive was based on a combination of wishful thinking and bad statistics, long before the Butt report.
In October 1940 Peirse told Portal that he thought between one in three and one in five aircraft despatched actually found the target, depending on range, yet in the 'Oil Plan' it was assumed that 50% of bombers despatched would actually bomb the target.
An oil plant could supposedly be put out of action for four months by just two hundred sorties aiming four hundred 500lb bombs at it, despite the fact that an early analysis of attacks on the two plants at Gelsenkirchen (by the Photographic Interpretation Section) which showed neither had received any significant damage despite being attacked by 162 and 134 aircraft and 159 tons and 103 tons of bombs (both excluding incendiaries) respectively.
Poor intelligence, like pilot claims, no matter how well filtered by intelligence officers at the time, leads to bad data. If the bad data is then combined with blinkered or wishful thinking by those empowered to act upon it the errors are compounded and can be very costly.
Cheers
Steve