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  "path": "/t/the-growing-interest-in-integrating-causal-inference-and-design-theory/28581#post_13",
  "publishedAt": "2026-05-13T21:45:10.000Z",
  "site": "https://discourse.datamethods.org",
  "textContent": "stephenrho:\n\n> have been trying to follow the various threads on here where this has been raised and still don’t understand how graphs like those above illuminate the real problem you have identified in critical care beyond a general (word-based) statement that \"average treatment effects are of little use, or are misleading, when there is (probably) substantial treatment effect heterogeneity\n\nStephen is this clear now?. It is confusing because classic HTE is within a single causal space. It is derived from the “second estimand” as a function of tau (x). This is a natural part of a RCT. We all understand that. As clinicians we consider outlier status in decision making.\n\nThe problem not understood (or not acknowledged) is the heterogeneity caused by mixing diseases or causes at the gate (as by using a symbolic gate, eg a syndrome) which is not specific for a cause or disease. This is the cause agnostic RCT (CAR) institutionalized about 1 year after I began my critical care practice. Unlike a true RCT, they are not safely transportable.\n\nThe term “cause agnostic” refers to the cause of the outcome targeted by the treatment. One could use the term “Disease Agnostic RCT”.\n\nThis modified RCT was never contemplated by Bradford Hill and generates an additional layer of heterogeneity which is not present in standard RCTs prior to 1987. (Although there may be earlier usages).\n\nThis image demonstrates cause or disease mixture heterogeneity and the cause mixture paradox which caused the COVID ventilator revolt in 2020. Here we can mathematically link clinical failure during the pandemic directly to a benign appearing modification of RCT methodology in 1987. No one will debate that.\n\nHere is a teaching image which I use to teach clinicians. This is a cause (disease) agnostic RCT of apples and oranges triaged by the selection gate of “round fruit”. This is analogous to a selection gate of the syndromes ARDS, Sepsis, or CAP based on triage thresholds.\n\nNote again this is not really an RCT in the true sense which requires a targetable cause in all the participants. (For Hill this was alveolar TB). This is a RCT mimic, a streamlined modified RCT which recruits (selects) patients by disease and causal mechanism agnostic triage making a high n easy but destroying safe transportability.",
  "title": "The growing interest in integrating causal inference and Design Theory"
}