On Unwin: The problem with his (to me, cutesy) equation is precisely what value you give to D, as he himself admits, "this number has a subjective element since it reflects my assessment of the evidence." It seems an exercise in silliness. It creates an entirely an arbitrary number (Why multiply by D? Why not D squared?) based on the beliefs of the person who uses it. It's like one of those online tests where you say what you think about God and it tells you what religion/denomination you should join, only it pretends a greater "accuracy" level than the online tests.