The effectiveness of preparation is not random. Charting the effectiveness of such efforts, were it possible to do so, might yield a random distribution; this does not, however, imply that "all of these secondary factors" can or should be "regarded as random" for anything more than a high-level treatment that becomes worthless in the (individual) context where it actually matters.
I tried to have a very light touch with the data. Most of what I do is non-parametric -- so in this sense, yes as an individual this analysis is only good if you believe there's some similarity between you and everyone that's ever been on the list (so a finite sample).
