A Longitudinal Renal Health Outcome for Clinical Trials in Acute Kidney Injury?

llynn:

the generation of non-disease specific ordinal scores

It’s interesting that you seem to identify ordinal scoring per se as a problem here, Lawrence. I had the opportunity to attend Frank’s latest online RMS course, and was deeply impressed by how ordinal cumulative probability models achieve a unification of so much antecedent work, as laid out in RMS §25.3. Any time something like this happens, one has to sit up and take notice. I even remarked to my friend @Drew_Levy that this felt “very ‘category theory’”.

Taking that quip seriously, I would return the Preface to Emily Riehl’s Category Theory in Context :

The category-theoretic perspective can function as a simplifying abstraction, isolating propositions that hold for formal reasons from those whose proofs require techniques particular to a given mathematical discipline.

(emphasis is mine)

We are sometimes insufficiently reflective about the nature and degree of the abstractions we are using. Much discussion of DAGs on Datamethods treats them as having an ontological status, rather than (properly) as high abstractions. I like Whitehead’s term fallacy of misplaced concreteness , discussed in this passage from Whitehead’s Process and Reality (Ch I, §III):

… the chief error in philosophy is overstatement. The aim at generalization is sound, but the estimate of success is exaggerated. There are two main forms of such overstatement. One form is what I have termed elsewhere, the ‘fallacy of misplaced concreteness’. This fallacy consists in neglecting the degree of abstraction involved when an actual entity is considered merely so far as it exemplifies certain categories of thought. There are aspects of actualities which are simply ignored so long as we restrict thought to these categories. Thus the success of a philosophy is to be measured by its comparative avoidance of this fallacy, when thought is restricted to its categories.

The other form of overstatement consists in a false estimate of logical procedure in respect to certainty, and in respect of premises. Philosophy has been haunted by the unfortunate notion that its method is dogmatically to indicate premises which are severally clear, distinct, and certain; and to erect upon those premises a deductive system of thought.

(emphasis again is mine)

Paraphrasing Riehl, I am inclined to think that we should take care not to look past “techniques particular to a given clinical discipline.” This holds especially true for Critical Care, whose underlying scientific basis — as distinct from its current research enterprise — has matured to a point that ought to open up marvelous opportunities. Consider that an ICU is a veritable human physiology laboratory, with an abundance of high-frequency, multivariate time-series.