Comments on "Surrogates measures and consistent surrogates" (by Tyler VanderWeele)
Abstract
I commend Professor VanderWeele for providing a lucid description of the "surrogate paradox" and, through it, a comprehensive discussion of the current state of thinking about surrogate endpoints, their function in experimental studies, and the various approaches devised to give them formal underpinnings. The first question that came to mind in reading VanderWeele's paper was: can we explain the phenomenon in simple terms, divorced from the technical vocabulary that was devised to formulate notions such as "indirect effect," "principled strata," "proportion-mediated," and perhaps others? My second question was: If we take the negation of the "surrogate paradox" as a criterion for "good" surrogate, why can't we create a new, formal definition of "surrogacy" that (1) will automatically avoid the paradox and (2) will settle, once for all, the disputes (among theoreticians) as to what "approach" is best for defining surrogates (Joffe and Green, 2009, pp. 530-538; Pearl, 2011). In thinking about these two questions, I came across a simple way of explaining how the paradox comes about and, indirectly, why the requirement of avoiding the paradox could not, in itself, constitute a satisfactory definition of surrogacy.
Document Details
- Document Type
- Technical Report
- Publication Date
- Mar 01, 2013
- Accession Number
- ADA578366
Entities
People
- Judea Pearl
Organizations
- University of California, Los Angeles