What is error rate in UX research?
Error rate tracks how often users make mistakes during task completion. Errors include selecting the wrong option, navigating to the wrong section, entering incorrectly formatted information, or misinterpreting interface elements. Error rate is expressed as the average number of errors per task per participant, or as the percentage of task attempts that included at least one error. A task can have a high completion rate but a high error rate, indicating that users eventually succeed but with significant difficulty.
How does error rate reveal interface design problems?
High error rates at specific points in a task flow identify where users are confused, where affordance is unclear, or where the interface creates mapping failures. If 70% of users incorrectly interact with a particular element before finding the correct path, that element's design is failing. Error rate data combined with observation of which specific errors users make provides diagnostic information that guides design improvements.
How to reduce error rates through design?
Applying error prevention principles reduces error rates by making incorrect actions less likely or more recoverable. Clear affordances reduce the frequency of users attempting non-interactive elements. Inline validation prevents users from submitting incorrect information. Confirmation dialogs for destructive actions prevent accidental errors. When errors do occur, specific error messages that explain what went wrong and how to correct it allow users to recover quickly.