A quantification of robustness

•The word robust, though regularly used in psychology, is rarely defined and never quantified.•This paper advances a method for quantifying robustness in cognitive science.•Our quantification demonstrates the robustness of decision-making heuristics.

Robustness is an important construct in domains as diverse as evolutionary biology, structural engineering, and decision-making. Unfortunately, in many domains, most relevantly cognitive science, considerations of robustness end with vague semantic references. Little attention is paid to formal analysis. The aim of this paper is to initiate a discussion in the scientific community regarding methods for quantifying and analyzing robustness. To this end, we propose a means for assessing robustness that may supplant the current ambiguous use of the term. We demonstrate our quantitative approach using examples of heuristic-based decision processes, selected due to their explicit association with robustness in the psychological literature. These examples serve to illustrate basic properties of our general methodology for quantifying robustness.