Are users performing tasks optimally? Are there ways to streamline and reduce the time it takes to complete the task?
How prone to errors is the task? What are the reasons for any errors? How can we improve the interface to lower errors and unneeded repetition?
If a user makes a mistake while performing the task, how fast can he recover?
How easy is the task to repeat?
Are interactive elements (such as buttons, links and input text boxes) related to the accomplishment of a task obviously interactive and within convenient reach? Is it evident what the results of a user action will be when the user decides to interact with it by clicking, mouse hovering, etc.?
Following Xavier University document highlights qualitative aspects associated with a project and how qualitative research is different from quantative research.