Key Usability Metrics

Key usability metrics are the quantitative measures used to evaluate how effectively, efficiently, and satisfyingly users can interact with a product. They provide objective, comparable data that tracks UX quality over time and across design iterations.

Researchers select metrics that align with the research question and the nature of the product. The most commonly used include: task completion rate (percentage of users who successfully complete a task), time on task (how long it takes), error rate (how often users make mistakes), and satisfaction scores.

Other widely used metrics include the System Usability Scale (SUS), a standardized questionnaire producing a 0–100 usability score; the Single Ease Question (SEQ), a quick post-task rating; Net Promoter Score (NPS); and Customer Effort Score (CES).

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