PJ2:
As such, I personally would have nothing further to say with respect to "killer items" as this thread covers them sufficiently
Thanks for your further clarification and patience. I will read the books you note. I think I might have misunderstood your original drift. Depending on the final outcome of the investigation of course, it is a little discouraging to know that nothing more can be done to eliminate human factors in such regard. Statistical significance having been understood.