We make sense of our complex and uncertain world with information about risk that is often presented in terms of probabilities, proportions, percentages and other ratio concepts.  Whether patients, consumers, and policy-makers correctly understand these risks—i.e., whether or not they are risk literate—depends in part on their statistical numeracy.  Accordingly, scientists have been working to understand the sources and implications of risk literacy and statistical numeracy (What is Numeracy?).

Here, we use statistical numeracy specifically to refer to an understanding of the operations of probabilistic and statistical computation, such as comparing and transforming probabilities and proportions.  These statistical aspects of numeracy are key features of risk assessment in business and engineering, and play central roles in health risk quantification and communication.  Moreover—although risk commonly refers to many topics (e.g., variability in probability distributions; the effect of uncertainty on objectives; exposure to danger and loss)—economic and psychological sciences have long held that decision making under risk is that involving known “statistical probabilities” and quantitative “probabilistic reasoning”.   In this way, statistical numeracy is one factor that gives rise to risk literacy—i.e., the ability to accurately interpret and act on information about risk.  Indeed, statistical numeracy has been shown to be a predictor of decision strategies,  emotional reactions, accurate comprehension and better choices across many risky economic, health, and consumer decisions.