Should I ask the user to complete the task as fast as she can in user test?

1. How do you measure task success rate?
2. Which among the following is not an important part of the usability testing?

How do you measure task success rate?

To report levels of success, you simply report the percentage of users who were at a given level. So, for example, if out of 100 users, 35 completed the task with a minor issue, you would say that 35% of your users were able to complete the task with a minor issue.

Which among the following is not an important part of the usability testing?

Because they do not allow you to actually observe visitors on the site in action, surveys are not considered usability testing—though they may be used in conjunction with it.