The latest issue of Wired magazine provides a great heads-up on random numbers by Jonathan Keats. Scrambling the order of runs is a key to good design of experiments (DOE)—this counteracts the influence of lurking variables, such as changing ambient conditions.
Designing an experiment is like gambling with the devil: only a random strategy can defeat all his betting systems.
– R.A. Fisher
Along those lines, I watched with interest when weather forecasts put Tampa at the bulls-eye of the projected track for Hurricane Isaac. My perverse thought was this might the best place to be, at least early on when the cone of uncertainty is widest.
In any case, one does best by expecting the unexpected. That gets me back to the topic of randomization, which turns out to be surprisingly hard to do considering the natural capriciousness of weather and life in general. When I first got going on DOE, I pulled numbered slips of paper out of my hard hat. Then a statistician suggested I go to a phone book and cull numbers from the last 4 digits from whatever page opened up haphazardly. Later I graduated to a table of random numbers (an oxymoron?). Nowadays I let my DOE software lay out the run order.
Check out how Conjuring Truly Random Numbers Just Got Easier, including the background by Keats on pioneering work in this field by British (1927) and American (1947) statisticians. Now the Australians have leap-frogged (kangarooed?) everyone, evidently, with a method that produces 5.7 billion “truly random” (how do they know?) values per second. Rad mon!