Figure 16 Sept 2026From “What is selection bias? The sample can change the answer”

The synthetic selection-bias eligibility ledger

The inclusion mechanism belongs beside the outcome. A sample label alone does not show whether the target comparison survived selection.

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Figure 1The synthetic selection-bias eligibility ledger

ID	Target and intended unit	Inclusion or conditioning event	Selected sample	Selection variable to inspect	Possible direction	Design response
S-01	All eligible trial accounts	Account completed setup	Setup completers only	Baseline capability and motivation	Unknown	Compare entry population; retain non-completers
S-02	All invited buyers	Survey response	Respondents	Interest and response burden	Unknown	Track nonresponse; compare frame variables
S-03	All routed leads	Sales acceptance	Accepted leads	Qualification and seller capacity	Could change both ways	Preserve rejected leads; model routing path
S-04	All campaign targets	Ad exposure	Exposed and holdout users	Targeting score and prior behavior	Likely selection risk	Random assignment or validated design
S-05	All open opportunities	Proposal reached	Proposal-stage records	Deal maturity and seller choice	Unknown	Report stage entry; do not call late-stage rate funnel-wide
S-06	All retained accounts	Remained observable through day 60	Day-60 responders	Early value and survival	Unknown	Treat attrition as a separate outcome and sensitivity

Swipe or scroll horizontally if the table is wider than your screen.

Source: Author's synthetic eligibility ledger grounded in Lewis and Rao (2015). Targets, selection paths, possible directions, tests, and dispositions are illustrative.

PNG4:3, 1600 × 1200, with the title, the source line and the attribution set in the image isoglu-2026-what-is-selection-bias-fig02.png

Source and evidence

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

A LR15-C3 Why observational methods fail here is an economics problem, in the authors' words: "The median confidence interval on return on investment is over 100 percentage points wide", so "informative advertising experiments can easily require more than 10 million person-weeks"Lewis & Rao (2015)
B R09-OWN-C1 Selection bias arises when the mechanism that puts units into the observed or analyzed sample is related to variables relevant to the target questionAuthor framework grounded in LR15-C3
B R09-OWN-C2 The target population, eligibility rule, observed sample, and conditioning event are different objects and must not be collapsed into one denominatorAuthor framework
B R09-OWN-C4 Conditioning on a common consequence of exposure and outcome predictors can create collider bias even when the initial variables were not associatedAuthor causal framework
B R09-OWN-C6 A selection review should name the target, inclusion path, excluded units, selection variables, expected direction if known, and design or sensitivity testAuthor operating framework
B R09-OWN-C7 The six-row eligibility ledger is synthetic and contains no participant, customer, employee, or company sampleAuthor synthetic object
B R09-OWN-C9 A changed eligibility rule can change the comparison set and raw rate without proving a change in the underlying outcome processAuthor negative boundary

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

From the essay

From the research bench

What is selection bias? The sample can change the answer

Selection bias begins with the inclusion mechanism. Name the target, eligibility rule, exclusions, and conditioning event before comparing outcomes.

6 Sept 2026

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This exhibit belongs to an essay: the numbers live here, the argument lives there.

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APA 7

Isoglu, S. (2026). The synthetic selection-bias eligibility ledger [Figure]. isoglu.com. https://isoglu.com/insights/exhibits/isoglu-2026-what-is-selection-bias-fig02/

BibTeX

@misc{isoglu-2026-what-is-selection-bias-fig02,
  author = {Isoglu, Sinan},
  title = {{The synthetic selection-bias eligibility ledger}},
  year = {2026},
  howpublished = {Figure 1, isoglu.com},
  url = {https://isoglu.com/insights/exhibits/isoglu-2026-what-is-selection-bias-fig02/},
  note = {From the essay {What is selection bias? The sample can change the answer}}
}

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<figure>
  <a href="https://isoglu.com/insights/exhibits/isoglu-2026-what-is-selection-bias-fig02/">
    <img src="https://isoglu.com/social/isoglu-2026-what-is-selection-bias-fig02.png" alt="Figure 1: The synthetic selection-bias eligibility ledger" width="3200" height="2400">
  </a>
  <figcaption>Figure 1: The synthetic selection-bias eligibility ledger. Source: Author&#39;s synthetic eligibility ledger grounded in Lewis and Rao (2015). Targets, selection paths, possible directions, tests, and dispositions are illustrative. <a href="https://isoglu.com/insights/exhibits/isoglu-2026-what-is-selection-bias-fig02/">View exhibit</a>.</figcaption>
</figure>