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MENTAL MODEL · M7613

Stopping Rule

Stopping Rule
CultureHigh supportChinese Philosophy
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Updated 2026-08-10

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INTRODUCTION

English translation pending.

CORE DEFINITION

In sequential analysis and clinical trials, a stopping rule defines the evidence state at which data collection ends. Group-sequential designs express it as boundaries, such as the O'Brien-Fleming or Pocock boundaries, that permit early stopping while holding the overall type I error rate at its nominal level. The key constraint is timing: the rule must be set before the data are seen, because a rule chosen or revised after peeking inflates false positives and distorts p-values and confidence intervals.

SCAFFOLDING EFFECT

psychology

Reduce cognitive load

- Fix it early: Write the sample size, effect threshold and stopping condition before collecting any data. - Correct for peeking: Use sequential boundaries whenever you must look at the data more than once. - Honour the trigger: Stop when the condition is met instead of continuing to justify sunk cost.

anchor

Anchor fast decisions

Every unplanned look at accumulating data is an extra test, so the chance of a false positive grows with the number of looks. A stopping rule counters this by distributing the total error budget across the planned analyses, so each interim check uses a stricter threshold and the overall error rate stays fixed. Pre-specification is what makes the result interpretable, because the boundary no longer depends on the data it judges.

MINIMUM ACTION

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Source support: Explicit

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    en.wikipedia.orghttps://en.wikipedia.org/wiki/Stopping_timeZH · Explicit
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