One of the best ways to understand what is and is not working in an interface is to monitor users as they use the interface.
How it works?
In a usability-testing session, a researcher, also called a “facilitator” or a “moderator” asks a participant to perform tasks, usually using one or more specific user interfaces. While the participant completes each task, the researcher observes the participant’s behavior and listens for feedback.
When to use?
You can use the usability test to uncover problems in the design, discover the opportunities and learn more about your users. Depending on the test scope and the requirements a simple wireframe could be also handy within the finished UI.
Formative testing is that forms and shapes a design for a user interface.
The nature of formative testing means that it is crucial to observe and understand the participants thought processes and their actions resulting from them.
Summative testing is about determining the issues, problems or benefits of an existing or prototype design.
Summative testing is more about measuring and counting. Examples include; recording the time it takes to understand and complete tasks , counting the number of clicks ,pauses or errors in either the system or the users’ comprehension of it.
User goal: Browse a product offerings and purchase an item.
Poor Task: Purchase a pair of orange Nike running shoes.
Better task: Buy a pair of shoes for less than $40.
User goal: Find movie for certain genre.
Poor task: You want to watch a horror movie. Go to netflix.com and tell me where you'd click next.
Better task: Use netflix.com to find a movie of your favourite genre.
User goal: Look up your grades.
Poor task: You want to see the results of your midterm exams. Go to the website, sign in and tell me where would you click to get your transcript.
Better task: Look up the results of your midterm exams.