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Figure 1From “What is external validity? A result needs a transfer boundary”

The external-validity transfer matrix

A result can be internally credible and still need a new argument before it is transported to a different target.

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Figure 1The external-validity transfer matrix

A six-row transfer worksheet with seven columns for ID, source or target object, treatment and comparator, outcome and time window, context, changed field, and transfer verdict.IDStablerowidentifier.Source or targetobjectSource result ornamed target.Treatment andcomparatorWhat was done,and against what?Outcome andwindowWhich event orconstruct, andwhen?ContextWhich operatingor institutionalsetting?Changed fieldPopulation,treatment, outcome,context, none;bridge?VerdictReplicate,transport,limit or not?Six rows are deliberate: one synthetic source result, one replication candidate, and four one-field target changes. Theillustrative plus-eight-point effect is not a benchmark.

Source: Author's synthetic transfer matrix grounded in Egami and Hartman (2023) and Campbell (1979). All rows, effects, and decisions are illustrative.

PNG4:3, 1600 × 1200, with the title, the source line and the attribution set in the image isoglu-2026-what-is-external-validity-fig03.png

Source and evidence

Each line names a claim related to this exhibit, its source, and how it was checked.

  • A EH23-C1 "we propose a formal framework that encompasses four dimensions of external validity x t y and c validity populations treatments outcomes and contexts"Egami & Hartman. (2023)
  • A EH23-C2 Two goals, not one: "effect generalization generalizing the magnitude of causal effects" and "sign generalization generalizing the direction of causal effects", each with its own estimators and assumptionsEgami & Hartman. (2023)
  • A EH23-C3 "effect generalization generalizing the magnitude of causal effects", for which the authors "introduce three estimators of the target population causal effects"Egami & Hartman. (2023)
  • A EH23-C4 "sign generalization generalizing the direction of causal effects", for which they "propose a novel multiple testing procedure under weaker assumptions": a different target needs a different toolEgami & Hartman. (2023)
  • B R01-OWN-C1 External validity is target-relative; a result does not possess universal transfer by itselfAuthor framework
  • B R01-OWN-C3 Changing one transfer field changes the target claim boundary before a verdict is offeredAuthor boundary
  • B R01-OWN-C4 A self-serve small-business experiment does not automatically answer an enterprise implementation targetAuthor synthetic illustration
  • B R01-OWN-C7 Replication, transport, and analogy are different decisions with different evidentiary burdensAuthor framework

Grades: A, verified against the printed page of the primary source · B, primary source, text layer only · C, authoritative secondary · D, reported.

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APA 7

Isoglu, S. (2026). The external-validity transfer matrix [Figure]. isoglu.com. https://isoglu.com/insights/exhibits/isoglu-2026-what-is-external-validity-fig03/

BibTeX
@misc{isoglu-2026-what-is-external-validity-fig03,
  author = {Isoglu, Sinan},
  title = {{The external-validity transfer matrix}},
  year = {2026},
  howpublished = {Figure 1, isoglu.com},
  url = {https://isoglu.com/insights/exhibits/isoglu-2026-what-is-external-validity-fig03/},
  note = {From the essay {What is external validity? A result needs a transfer boundary}}
}
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<figure>
  <a href="https://isoglu.com/insights/exhibits/isoglu-2026-what-is-external-validity-fig03/">
    <img src="https://isoglu.com/social/isoglu-2026-what-is-external-validity-fig03.png" alt="Figure 1: The external-validity transfer matrix" width="3200" height="2400">
  </a>
  <figcaption>Figure 1: The external-validity transfer matrix. Source: Author&#39;s synthetic transfer matrix grounded in Egami and Hartman (2023) and Campbell (1979). All rows, effects, and decisions are illustrative. <a href="https://isoglu.com/insights/exhibits/isoglu-2026-what-is-external-validity-fig03/">View exhibit</a>.</figcaption>
</figure>