Success rate is a fundamental usability metric that indicates the percentage (%) of users (p) who successfully complete a task. Success is typically defined by the ability to complete a task without human intervention to aid or instruct. This metric is extremely limited in the sense it doesn’t measure why users succeed or how well they perform the task they completed. It’s also critical to determine the definition of the task and success to be as clear and straightforward as possible.
Out of 500 users total performing a given task, 390 complete the task successfully yielding a 78% successful task completion rate.
This is an important metric used to understand the usability of a feature. Does the interaction design make sense to the user in a way they can complete the task as intended? A prototype testing tool such as Maze will yield task success rate for a specific task provided.
For example:
Task - Create a new post
Success - When the user clicks submit and receives confirmation a new post has been created.
A usability prototype would allow you to test how many participants that attempt the task actually succeed to understand if the design makes sense in practice. Typically a 80+% success rate is considered good usability and 90%+ is considered excellent.
Research and design should lead the measurement of this metric in all usability testing and prototypes using tools like Maze.This metric is usually associated with and influenced by: