When played as a game, the purpose is rarely for the organizer to get a good estimate. It’s either for entertainment or for point-scoring by the participants. As such, the bracketing strategy is just part of the fun. If you want to “fix” it, just make it simultaneous—you get better information about independent estimates, and you remove (some of) the strategic adjustment of guesses.
You could also give up the “one winner” idea—scoring based on distance from actual (or better, by impact of error, which can vary by topic), without caring whether someone else was closer, would incent true estimate submission.
Finally, why not just set up a betting market? Let participants weight their estimates by strength of information.
When played as a game, the purpose is rarely for the organizer to get a good estimate. It’s either for entertainment or for point-scoring by the participants. As such, the bracketing strategy is just part of the fun. If you want to “fix” it, just make it simultaneous—you get better information about independent estimates, and you remove (some of) the strategic adjustment of guesses.
You could also give up the “one winner” idea—scoring based on distance from actual (or better, by impact of error, which can vary by topic), without caring whether someone else was closer, would incent true estimate submission.
Finally, why not just set up a betting market? Let participants weight their estimates by strength of information.