This week, we welcome Benedicte Colnet from INRIA, invited by Prof.
Chris Holmes, to give a talk in our OxCSML seminar. Details are below,
looking forwards to seeing you there.
Hai-Dang.
Speaker: Benedicte Colnet (INRIA France)
Time and date: 16.00 - 17.00, Friday 19 May 2023
Place: Small Lecture Theatre (LG03), Department of Statistics, University of Oxford
Zoom registration link:
https://www.eventbrite.co.uk/e/oxcsml-seminar-19-may-2023-benedicte-colnet-tickets-634731718657
Title: Risk ratio, odds ratio, risk difference... Which causal measure is easier to generalize?
Abstract: There are many measures to report so-called treatment or
causal effect: absolute difference, ratio, odds ratio, number needed to
treat, and so on. The choice of a measure, e.g. absolute versus
relative, is often debated because it leads to different
appreciations of the same phenomenon; but it also implies different
heterogeneity of treatment effect. In addition some measures -- but not
all -- have appealing properties such as collapsibility, matching the
intuition of a population summary. We review common
measures and their pros and cons typically brought forward. Doing so,
we clarify notions of collapsibility and treatment effect heterogeneity,
unifying different existing definitions. Our main contribution is to
propose to reverse the thinking: rather than
starting from the measure, we start from a non-parametric generative
model of the outcome. Depending on the nature of the outcome, some
causal measures disentangle treatment modulations from baseline risk.
Therefore, our analysis outlines an understanding
what heterogeneity and homogeneity of treatment effect mean, not
through the lens of the measure, but through the lens of the covariates.
Our goal is the generalization of causal measures. We show that
different sets of covariates are needed to generalize
an effect to a different target population depending on (i) the causal
measure of interest, (ii) the nature of the outcome, and (iii) the
generalization's method itself (generalizing either conditional outcomes
or local effects).