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A better approch?

Posted By: Timothy Chow
Date: Monday, 2 November 2009, at 6:40 p.m.

In Response To: A better approch? (eXtreme Gammon)

If you really want to report your result as "the probability that play X is the best" then I think you should really use a Bayesian approach, as I explained in a post I made here a couple of months ago.

If you think about it closely, calculating some tail region in a multidimensional Gaussian with the estimated parameters you listed does not answer the question, "What is the probability that this play is the best?" When you write down those means and standard deviations, what you're saying is, "This is my best estimate of the mean and standard deviation of the equity of this move." The tail probability is then telling you the probability of some rare event happening, given that your estimated mean and standard deviation are accurate. But this is the opposite of the question you really want to ask. You want to know, what is the probability that I would see the results I am actually observing, given that this lower-scoring play is in fact the best one?

The only way to answer the latter question is to fix some prior probabilities and update those probabilities as you accumulate evidence.

Messages In This Thread

• Confidence Interval Overlap vs Joint Standard Deviation (long)
  neilkaz -- Saturday, 31 October 2009, at 5:13 p.m.
  • Confidence Interval Overlap vs Joint Standard Deviation (long)
    Timothy Chow -- Saturday, 31 October 2009, at 5:30 p.m.
  • Confidence Interval Overlap vs Joint Standard Deviation (long)
    Tom Keith -- Saturday, 31 October 2009, at 5:51 p.m.
    • Confidence Interval Overlap vs Joint Standard Deviation (long)
      Rich Munitz -- Sunday, 1 November 2009, at 3:19 a.m.
  • Confidence Interval Overlap vs Joint Standard Deviation (long)
    Bob Koca -- Saturday, 31 October 2009, at 7:30 p.m.
    • Confidence Interval Overlap vs Joint Standard Deviation (long)
      neilkaz -- Saturday, 31 October 2009, at 9:20 p.m.
      • Confidence Interval Overlap vs Joint Standard Deviation (long)
        Bob Koca -- Saturday, 31 October 2009, at 9:31 p.m.
      • Confidence Interval Overlap vs Joint Standard Deviation (long)
        Timothy Chow -- Sunday, 1 November 2009, at 12:21 a.m.
  • A better approch?
    eXtreme Gammon -- Sunday, 1 November 2009, at 4:02 a.m.
    • A better approch?
      neilkaz -- Sunday, 1 November 2009, at 4:32 a.m.
    • A better approch?
      MaX -- Sunday, 1 November 2009, at 1:19 p.m.
    • A better approch?
      MaX -- Sunday, 1 November 2009, at 1:22 p.m.
    • A better approch?
      Timothy Chow -- Sunday, 1 November 2009, at 5:37 p.m.
      • A better approch?
        eXtreme Gammon -- Sunday, 1 November 2009, at 6:12 p.m.
        • A better approch?
          Bob Koca -- Sunday, 1 November 2009, at 7:36 p.m.
          • A better approch?
            Tom Keith -- Sunday, 1 November 2009, at 8:38 p.m.
            • A better approch?
              Chuck Bower -- Monday, 2 November 2009, at 1:20 a.m.
              • A better approch?
                Jason Lee -- Monday, 2 November 2009, at 2:24 a.m.
                • A better approch?
                  Chuck Bower -- Monday, 2 November 2009, at 3:06 p.m.
              • A better approch?
                Timothy Chow -- Monday, 2 November 2009, at 6:56 p.m.
        • A better approch?
          Maik Stiebler -- Sunday, 1 November 2009, at 10:05 p.m.
        • A better approch?
          MaX -- Monday, 2 November 2009, at 10:15 a.m.
          • A better approch?
            Timothy Chow -- Monday, 2 November 2009, at 6:47 p.m.
            • A better approch?
              MaX -- Tuesday, 3 November 2009, at 8:18 a.m.
          • A better approch?
            eXtreme Gammon -- Monday, 2 November 2009, at 7:26 p.m.
            • A better approch?
              MaX -- Thursday, 12 November 2009, at 12:56 p.m.
        • A better approch?
          Timothy Chow -- Monday, 2 November 2009, at 6:40 p.m.
          • A better approch?
            Tom Keith -- Monday, 2 November 2009, at 7:28 p.m.
            • A better approch?
              Timothy Chow -- Monday, 2 November 2009, at 10:10 p.m.
              • A better approch?
                Tom Keith -- Tuesday, 3 November 2009, at 12:14 a.m.
                • A better approch?
                  Timothy Chow -- Tuesday, 3 November 2009, at 1:29 a.m.
                  • A better approch?
                    Maik Stiebler -- Tuesday, 3 November 2009, at 7:18 a.m.
                    • A better approch?
                      Timothy Chow -- Tuesday, 3 November 2009, at 4:17 p.m.
                      • A better approch?
                        Tom Keith -- Tuesday, 3 November 2009, at 5:23 p.m.
                        • A better approch?
                          Timothy Chow -- Tuesday, 3 November 2009, at 5:37 p.m.
                          • Aren't you two just particpating in the 250 year old fracas?
                            Chuck Bower -- Tuesday, 3 November 2009, at 6:19 p.m.
                            • Aren't you two just particpating in the 250 year old fracas?
                              Timothy Chow -- Tuesday, 3 November 2009, at 7:55 p.m.
                              • Aren't you two just particpating in the 250 year old fracas?
                                Bob Koca -- Tuesday, 3 November 2009, at 8:29 p.m.
                            • Aren't you two just particpating in the 250 year old fracas?
                              Tom Keith -- Wednesday, 4 November 2009, at 12:11 p.m.
                      • A better approch?
                        Maik Stiebler -- Wednesday, 4 November 2009, at 8:40 p.m.
                        • A better approch?
                          Timothy Chow -- Wednesday, 4 November 2009, at 10:09 p.m.
                          • A better approch?
                            Maik Stiebler -- Wednesday, 4 November 2009, at 10:51 p.m.
                            • A better approch?
                              Maik Stiebler -- Wednesday, 4 November 2009, at 11:57 p.m.
                            • A better approch?
                              Timothy Chow -- Thursday, 5 November 2009, at 6:52 a.m.
                              • A better approch?
                                Maik Stiebler -- Thursday, 5 November 2009, at 7:25 a.m.
                                • A better approch?
                                  Timothy Chow -- Thursday, 5 November 2009, at 3:37 p.m.
                                  • A better approch?
                                    Maik Stiebler -- Thursday, 5 November 2009, at 9:19 p.m.
                                    • A better approch?
                                      Maik Stiebler -- Thursday, 5 November 2009, at 9:42 p.m.
          • A better approch? [LONG]
            MaX -- Thursday, 5 November 2009, at 3:04 p.m.
            • A better approch? [LONG]
              Timothy Chow -- Thursday, 5 November 2009, at 3:47 p.m.
            • A better approch? [LONG]
              Maik Stiebler -- Thursday, 5 November 2009, at 10:01 p.m.
              • A better approch? [LONG]
                MaX -- Friday, 6 November 2009, at 3:31 p.m.
                • A better approch? [LONG]
                  Maik Stiebler -- Saturday, 7 November 2009, at 5:52 p.m.
                  • A better approch? [LONG]
                    MaX -- Monday, 9 November 2009, at 12:39 p.m.
                    • A better approch? [LONG]
                      Maik Stiebler -- Monday, 9 November 2009, at 10:59 p.m.
                      • A better approch? [LONG]
                        MaX -- Tuesday, 10 November 2009, at 1:33 p.m.
        • A better approch?
          Tom Keith -- Thursday, 5 November 2009, at 10:23 p.m.
          • A better approch?
            MaX -- Friday, 6 November 2009, at 12:35 p.m.
    • A better approch?
      Bob Koca -- Sunday, 1 November 2009, at 7:45 p.m.
      • A better approch?
        eXtreme Gammon -- Sunday, 1 November 2009, at 10:03 p.m.
        • A better approch?
          Bob Koca -- Sunday, 1 November 2009, at 10:30 p.m.
    • A better approch?
      Mislav Radica -- Monday, 2 November 2009, at 12:59 a.m.
      • A better approch?
        eXtreme Gammon -- Monday, 2 November 2009, at 1:58 a.m.
        • A better approach?
          eXtreme Gammon -- Monday, 2 November 2009, at 2:00 a.m.
        • A better approch?
          MaX -- Monday, 2 November 2009, at 10:19 a.m.
        • A better approch?
          Mislav Radica -- Monday, 2 November 2009, at 12:55 p.m.
          • The different approachs-give us a choice
            Mislav Radica -- Monday, 2 November 2009, at 1:18 p.m.
        • A better approch?
          misja -- Monday, 2 November 2009, at 7:36 p.m.
    • A better approch?
      Neil Robins -- Tuesday, 3 November 2009, at 9:39 p.m.