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Researcher degrees of freedom

The decisions an analyst makes during a study (inclusion criteria, outcome definition, model specification, covariate set) any of which, if made differently, would yield a different result.

ByCASRAI Editorial Board

· Last updated 21 May 2026

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Examples

Worked examples

Is an instance
A catalogue of 34 binary choices an analyst could have made in a behavioural-economics study.
Is an instance
A registered report locking each of these choices in advance.

Counter-examples

Looks similar, but isn't

Not an instance
A coin flip (no analyst decisions involved).
Not an instance
A pre-specified single-model analysis (degrees of freedom collapsed to one).

Editorial commentary

Simmons, Nelson, and Simonsohn (2011) coined the term to explain why nominally well-conducted studies could nevertheless yield false positives at far above the nominal 5% rate. Researcher degrees of freedom are the substrate on which p-hacking, HARKing, and the garden of forking paths all act. Pre-registration constrains them; multiverse analyses expose their effect.

References

Simmons, Nelson, Simonsohn, 'False-positive psychology' (Psychological Science, 2011); Wicherts et al., 'Degrees of freedom in planning, running, analyzing, and reporting psychological studies' (Frontiers in Psychology, 2016).

Also known as

analytic degrees of freedom

Machine-readable encodings

Use in your systems

JATS XML <role> element

xml

<role vocab="credit"
      vocab-identifier="https://casrai.org/dictionary/"
      vocab-term="Researcher degrees of freedom"
      vocab-term-identifier="https://casrai.org/dictionary/term/researcher-degrees-of-freedom" />

Schema.org DefinedTerm (JSON-LD)

json

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  "@type": "DefinedTerm",
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  "name": "Researcher degrees of freedom",
  "identifier": "https://casrai.org/dictionary/term/researcher-degrees-of-freedom",
  "description": "The decisions an analyst makes during a study (inclusion criteria, outcome definition, model specification, covariate set) any of which, if made differently, would yield a different result.",
  "inDefinedTermSet": "https://casrai.org/dictionary/domain/reproducibility#set",
  "url": "https://casrai.org/dictionary/term/researcher-degrees-of-freedom",
  "sameAs": [
    "analytic degrees of freedom"
  ],
  "license": "https://creativecommons.org/licenses/by/4.0/",
  "publisher": {
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  },
  "dateModified": "2026-05-21T02:22:50",
  "inLanguage": "en"
}

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