Zebra Factor
The Zebra Factor is an arbitrary representation which determines to what degree an actual outcome is deviant to an expected outcome within the facts presented. Based on the idea that when all signs point to a horse, it may still be a zebra. Ancillary to Occam's Razor.
"You learn the Zebra Factor in first year medical school; when you hear hoof beats, think horses, not zebras." - House MD