Bayes isn’t magic

If a study is completely infeasible using traditional statistical methods, Bayesian methods are probably not going to rescue it. Bayesian methods can’t squeeze blood out of a turnip.

The Bayesian approach to statistics has real advantages, but sometimes these advantages are oversold. Bayesian statistics is still statistics, not magic.

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7 comments on “Bayes isn’t magic
  1. TriSys says:

    Well, HP must think otherwise and are paying billions of dollars for Autonomy, our Cambridge Business Park next door neighbours. Autonomy was founded by a Cambridge academic and is based exclusively on Bayesian mathematics for information retrieval.

  2. John says:

    @TriSys: I don’t know whether HP’s expenditure is justified or not.

    I work in Bayesian statistics and there are problems that I can only imagine solving with a Bayesian approach. But Bayesian methods can’t defy gravity.

    If you don’t have much information (either data or prior knowledge) then you can’t draw strong conclusions no matter what brand of statistics you practice. This should go without saying. It’s remarkable that some people have gone from an unjustified suspicion of Bayesian methods to unjustified optimism.

  3. F. Carr says:


    It’s remarkable that some people have gone from an unjustified suspicion of Bayesian methods to unjustified optimism.

    Possibly they have a poorly-informed prior.

  4. To really squeeze blood out of a statistical turnip you need state-space models! ()

  5. That was mean to be a "", not a

  6. Yang says:

    @John: is there something in particular that you may be referring to? Or an example of this optimism?

  7. The typical version I’ve encountered is the unbounded enthusiasm for modeling things you have no information for. I think people tend to understand the mechanics for simulation from a posterior in complex models long before they understand where information for specific parameters comes from. Then it’s easy to fall into the trap of modeling the state (esp. in state-space models) of something you have no information on (other than priors). I assume this is similar to what John’s comment is—you can only analyze something if your study design got you information on it. Specifically information which is not completely confounded with something else.

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