Cognitive Scaffold

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MENTAL MODEL · M0013

German Tank Problem

German Tank Problem
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Version 1.0.0 · Updated 2026-07-28

CORE DEFINITION

The German tank problem estimates N from observed identifiers under a model of items numbered 1 through N and uniform random sampling without replacement. It is named after the Allies’ historical use of captured equipment serial numbers to estimate German production in World War II.

SCAFFOLDING EFFECT

psychology

Reduce cognitive load

Use sequential identifiers to estimate population size when numbering and sampling assumptions are reasonable, making uncertainty explicit.

anchor

Anchor fast decisions

The sample maximum m generally falls below the population bound N. For k observations sampled uniformly without replacement from 1 through N, m + m/k - 1 is unbiased for N. The sample minimum cannot simply replace the maximum.

MINIMUM ACTION

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Source support: Explicit

  • link
    zh.wikipedia.orghttps://zh.wikipedia.org/wiki/%E5%BE%B7%E5%9B%BD%E5%9D%A6%E5%85%8B%E9%97%AE%E9%A2%98ZH · Explicit
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  • link
    en.wikipedia.orghttps://en.wikipedia.org/wiki/German_tank_problemEN
    verified

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