How Not to Be Wrong: The Hidden Mathematics of Everyday Life explains how mathematical thinking can be applied beyond formal calculations to problems encountered in public life and everyday decisions. Ellenberg uses examples from politics, economics, medicine, sport and other fields to show how numbers can illuminate questions but can also mislead when assumptions, context or statistical relationships are misunderstood.

The book examines ideas including regression to the mean, probability, correlation, statistical significance and the interpretation of data. It considers subjects such as opinion polling, election results, lotteries and scientific research, often using historical examples to trace how mathematical concepts developed. Ellenberg’s central argument is that mathematics is not simply a collection of formulas but a disciplined way of reasoning about uncertainty, patterns and evidence. The book is aimed at general readers and presents advanced ideas largely without technical notation.