On Feb 14, 2014, at 10:23 AM, Christopher Green wrote:
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. I agree, and that's fine and good, technically. But, there is a major practical problem we all face, that replications are not generally publishable, and even if publishable, is not the stuff of which tenure is made at Tier 1 Research Universities. So, you have one study on which to show your phenomenon is real. It has to be non-obvious enough to get you down the tenure track, but known well enough that prior probabilities are decently high… oh, and be something that you are interested in, for which data can be gathered in a short enough time period, etc. Good luck with finding that unicorn-esque project, much less executing it. The culture is not just a wide-spread attitude. The culture is in synergistic relationship with systems that discourage use of anything but traditional statistical thinking. When such a tightly integrated system exists, changing it is nigh impossible. What will cause it to change is one of two things: 1) A catastrophic failure/scandal such that the entire enterprise needs to be overhauled (e.g., the appalling use of research participants that leads to the Belmont Report). That seems unlikely because it will be too difficult to show lives destroyed by misapplication of statistical procedures/approaches. (I wonder if that was Bem's goal with the precognition paper, to provide results so bizarre through routine statistical approach that it would embarrass and 'shake up the business'.) 2) Psychology being supplanted by other disciplines that use more sophisticated methods and begin to make greater advances and have greater practical effect. At a certain point people may realize we are being made irrelevant and after years of anxious hand-wringing some kinds of fixes will be implemented, hopefully not too late. Or, we can fix it now. If I were editor of a journal I would simply require parallel results and discussion sections. One traditional in approach, the other Bayesian in approach. This would allow folks who are embedded in the past to continue their work the way they always have, but allow those who want to move to new approaches to do so. Eventually, if the Bayesian approach yields more useful interpretations of the data, it will become apparent and we should see changes occur in what is taught to students. As soon as there is a predominance of researchers who are Bayesian in approach the shift will be complete and we will see journals dropping the requirements for traditional approaches. We will all be dead before this happens, of course. Paul --- 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=34207 or send a blank email to leave-34207-13090.68da6e6e5325aa33287ff385b70df...@fsulist.frostburg.edu
