On 2014-02-13, at 10:38 AM, Paul C Bernhardt wrote: > > My only problem with the Bayesian approach, described elegantly in the > article, is that the posterior probabilities are so dependent on the prior > probabilities.
I hear this all this time, but I disagree. Even wildly divergent priors converge fairly rapidly in the face of the same data. In any case, priors are not necessarily reflective of mere "bias." They are often reflective of true expertise that has been developed informally in a field. To use a classic example, if you want to know what the probability is that two countries will go to war over, say, the next decade, do you think it is better to start with the base probability that ANY two random countries will go to war, or would you rather start with the estimate of people who are already expert in the history, cultures, and economies of the two countries in question? Bayesian prior, when used properly, actually SHORTEN the time to decision, not distort it. A very good non-technical introduction to (the history of) Bayesian theory can be found in Sharon Bertsch McGrayne's book, _The Theory that Would Not Die_ (http://www.amazon.com/The-Theory-That-Would-Not/dp/0300188226). It turns out that, academic statisticians' long-time resistance to Bayes notwithstanding, it was the standard being used covertly by governments and some industries for decades... because it works. Not known until recently (because it was a UK gov't secret), Bayeianism was actually at the root Alan Turing's work on code cracking during WWII. (Amazingly, even John Tukey was a Bayesian in his secret gov't work, though not in his public academic work.) > But, it would require a huge cultural shift that I am not sure we are willing > do to. One of many problems with psychology's "culture." It is amazing that people have been arguing for Bayesian statistics in psychology since the 1960s, but the discipline has steadfastly resisted while the world changes around it, isolating its archaic statistical rituals. There might have been some practical justification when one had to do hand computations, but with the rise of small, inexpensive, powerful computers in the 1980s, those excuses are no longer valid. Chris --- Christopher D. Green Department of Psychology York University Toronto, ON M3J 1P3 Canada [email protected] http://www.yorku.ca/christo/ ========================= --- You are currently subscribed to tips as: [email protected]. To unsubscribe click here: http://fsulist.frostburg.edu/u?id=13090.68da6e6e5325aa33287ff385b70df5d5&n=T&l=tips&o=34206 or send a blank email to leave-34206-13090.68da6e6e5325aa33287ff385b70df...@fsulist.frostburg.edu
