The only actual evidence one way or the other that I’m aware of is that of the Touring Plans team.Many people have pointed out that many of us never waited in standby lines. Getting FP was too easy. Also, based on much of the data provided there is no evidence that FP does significantly increase standby waits. In fact most of the evidence suggests that people that use FP, do overall spend less time waiting.
Is there other such evidence out there, as in measured wait times across entire days and analysed by statisticians? Or by evidence do you mean just lots of individuals sharing their own experience?