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  "path": "/t/collider-in-rct-subgroup-analysis/28689#post_17",
  "publishedAt": "2026-05-18T20:25:21.000Z",
  "site": "https://discourse.datamethods.org",
  "textContent": "As a clinician/researcher for 40 yrs one of the most important thing I have learned is to distinguish real biological data-generating processes (BDGPs) from synthetic data-generating processes (SDGPs). An SDGP is a gate-generated analytical construct that does not correspond to a single coherent biological causal system.\n\nYour paper is provocative and deeply insightful because it appears interpretable within the SDGP framework as describing the creation of a post-treatment SDGP. Traditional cause-agnostic syndrome RCTs create SDGPs upstream through consensus enrollment gates (e.g., sepsis, ARDS), whereas under your framework treatment-responsive subgrouping appears to create SDGPs downstream by conditioning on treatment-associated pathway states or biomarker responses.\n\nIn both cases, the analytical population is generated by conditioning on a gate rather than by identifying a coherent biological causal system. The resulting estimands become structurally unstable, composition-dependent quantities that may reverse or vary despite unchanged underlying biology.\n\nThus syndrome disease-mixing and post-treatment response grouping may represent parallel manifestations of synthetic gate conditioning occurring at different temporal locations within the causal structure.\n\nAn important implication is that pre-specification of a subgroup may not rescue the analysis if the subgroup itself constitutes a SDGP. Pre-specification does not eliminate structural instability arising from synthetic conditioning.",
  "title": "Collider in RCT Subgroup Analysis"
}