model complexity

One of the reasons I am interested in the exoplanet radial velocity stuff is that I am interested in model complexity: How to compare, combine, and decide among models of different complexity. I realized that the correct hierarchy of complexities is not based purely on the number of planets, but also on whether or not they are permitted to travel on orbits of nonzero eccentricity. I modified my code to respect this additional level of complexity and am re-running it all.


  1. Don't you need to be able to calculate Bayesian evidence in order
    to make a choice between model of different complexity?

  2. Anonymous: Yes, but the evidence only tells you how to *weight* the two models in a *mixture*. To make any hard decision, you need to specify utility and apply a decision-making process.

  3. Very interesting.. Is there a good reference with an
    example of how this is done?

  4. Anonymous: Not that I know of; this is one of the reasons I have been thinking about it.