Comparing belief certainty formats in the measurement of political knowledge

Abstract Psychological certainty plays a role in how respondents retrieve and express their attitudes, beliefs, and opinions. This study compares two question formats that allow respondents to express certainty about their political knowledge. Using a YouGov sample ( N = 2,161), a single-item certainty-in-knowledge format, where political knowledge and belief certainty are measured jointly, and a branching format, where knowledge is measured first, followed by certainty in a separate question, are compared. The results show that the certainty-in-knowledge format significantly reduces the likelihood of respondents looking up answers online. Including a “Don’t Know” option does not increase gender differences. These findings demonstrate a question format that improves validity in online surveys by reducing measurement artifacts.