I whole-heartedly agree with not taking someones word for something just because of a piece of paper, or even a real-world reputation. However, in this case, the PhD in question has enough of a reputation, a body of work and a proven track record.

Add to that, my own abilities in this area were never sufficient to even begin to fully comprehend the ideas, never mind challenge them. To that end, it becomes imprudent if not impossible to "Examine what is said".

It is impossible to be fully conversant in every field, and there will always be those subject areas where you simply have to rely upon the words and skills of others. Once this point is reached it becomes a case of trying to pick the people whos words, ideas & skills you put your trust in as wisely as possible. Examining their words in the light of their peers reactions to them, and the faith they place in them, is as good a way as any I know, and better than most:)

It is an imperfect mechanism. Even the historically judged "best and brightest in their fields" tend to be superceded over time, though it tends to be in the detail rather than in any fundemental way.

That said. I never met Mandlebrot, though I did watch a live presentation he gave once (to do with fractals), and I am pretty sure that he didn't have any direct involvement in the project in question. It is quite possible that the people that performed the statistics in question misunderstood his theories, or mis-applied them. I can atest to the accuracy of the predictions that the process produced albeit over a relatively short timeframe. Being fundementally an empiricist, it is this last point that is the strongest influence upon my faith in the methodology used.