Interesting thing about anecdotal data is I tend to hugely overestimate my effect in making people better. To bring myself back to earth I look at the puny effects many treatments have been demonstrated to have and conclude many patients get better regardless of treatment. I certainly underestimate my faults too, but that's a tougher nut to crack. I've also seen doctors overestimate other doctor's faults; of course the failure to intervene with a treatment shown to avoid a bad outcome by a few percentage points killed the patient!