What Is Your Estimand? Defining the Target Quantity Connects Statistical Evidence to Theory

We make only one point in this article. Every quantitative study must be able to answer the
question: what is your estimand? The estimand is the target quantity—the purpose of the
statistical analysis. Much attention is already placed on how to do estimation; a similar degree
of care should be given to defining the thing we are estimating. We advocate that authors
state the central quantity of each analysis—the theoretical estimand—in precise terms that
exist outside of any statistical model. In our framework, researchers do three things: (1) set
a theoretical estimand, clearly connecting this quantity to theory; (2) link to an empirical
estimand, which is informative about the theoretical estimand under some identification
assumptions; and (3) learn from data. Adding precise estimands to research practice expands
the space of theoretical questions, clarifies how evidence can speak to those questions, and
unlocks new tools for estimation. By grounding all three steps in a precise statement of the
target quantity, our framework connects statistical evidence to theory.

journals.sagepub.com/doi/10.1177/00031224211004187