Students, as well as teachers, often learn what makes sense to them, even when it is wrong. These misconceptions are a problem. The authors sought a quick, quantitative way of identifying student misconceptions in secondary science. Using the University of Toronto's National Biology Competition test data, this article presents a method of quickly identifying misconceptions that agree with many facets of the extant misconception literature (ubiquity across subject areas, pervasiveness regardless of question difficulty, and distractive power). Seeking students' most common wrong answer on a multiple-choice test is found to be a fast, reliable, and data-driven way to identify misconceptions.