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72-game rollouts in XG

Posted By: Timothy Chow
Date: Sunday, 1 May 2011, at 8:29 p.m.

Often I watch the first few trials of an XG rollout to get a sense of how large the confidence interval is, so that I can decide how many trials I want to roll out. One thing I've noticed is that frequently there is a very sharp drop in the size of the confidence interval at exactly 72 games. That is, the reported confidence interval after 72 games will be dramatically less than the reported confidence interval after 71 games.

This is very puzzling to me, as I can't think of any reason why this should happen. So my first question is, can anyone else confirm my observation? And if so, what is the explanation? Not a bug, I hope?

Messages In This Thread

• 72-game rollouts in XG
  Timothy Chow -- Sunday, 1 May 2011, at 8:29 p.m.
  • 72-game rollouts in XG
    neilkaz -- Sunday, 1 May 2011, at 9:26 p.m.
    • 72-game rollouts in XG
      Timothy Chow -- Monday, 2 May 2011, at 4:02 p.m.
  • 72-game rollouts in XG
    eXtreme Gammon -- Sunday, 1 May 2011, at 10:59 p.m.
    • 72-game rollouts in XG
      Bob Koca -- Monday, 2 May 2011, at 1:58 a.m.
      • 72-game rollouts in XG
        eXtreme Gammon -- Monday, 2 May 2011, at 2:07 a.m.
    • 72-game rollouts in XG
      Bob Koca -- Monday, 2 May 2011, at 2:00 a.m.
      • 72-game rollouts in XG
        eXtreme Gammon -- Monday, 2 May 2011, at 2:09 a.m.
        • 72-game rollouts in XG
          Neil Robins -- Monday, 2 May 2011, at 11:56 a.m.
        • 72-game rollouts in XG
          Timothy Chow -- Monday, 2 May 2011, at 10:03 p.m.
          • 72-game rollouts in XG
            eXtreme Gammon -- Tuesday, 3 May 2011, at 1:39 a.m.
            • 72-game rollouts in XG
              Neil Robins -- Tuesday, 3 May 2011, at 11:42 a.m.
              • 72-game rollouts in XG
                eXtreme Gammon -- Tuesday, 3 May 2011, at 2:09 p.m.
            • 72-game rollouts in XG
              Timothy Chow -- Tuesday, 3 May 2011, at 3:27 p.m.
            • 72-game rollouts in XG
              Timothy Chow -- Monday, 23 May 2011, at 2:41 p.m.
              • 72-game rollouts in XG
                eXtreme Gammon -- Monday, 23 May 2011, at 3:53 p.m.