The monthly puzzle · Sep 2026
Beneath the surface
A small monthly test of how you think about structure, probability and edge. No prizes — just the satisfaction of getting it out.
This month's puzzle Draft
[PLACEHOLDER] A survey ship takes three independent depth soundings of the same point on the seabed. Each sounding is unbiased but noisy, with the same error distribution. You may keep the average of the three, or discard the reading furthest from the other two and average the remaining pair. Under what condition on the noise is the "discard the outlier" rule the better estimator — and when does it quietly make you worse off?
Hint: think about what "furthest from the other two" is really selecting on, and whether the noise has fat tails.
Solution published with next month's puzzle. DRAFT — placeholder content.
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