Usability

Usability is a key component of the User Centered Design approach as a quality attribute that assesses how easy user interfaces are to use. Usability can be defined by 5 quality components (Jakob Nielsen):

  • Learnability
  • Efficiency
  • Memorability
  • Satisfaction
  • Errors

How easy is it for users to accomplish basic tasks the first time they encounter the design? how much do users have the think!

Once users have learned the design, how quickly can they perform the same and new tasks?

When users return to the design after a period of not using it, how easily can they reestablish proficiency?
How many errors do users make, how severe are these errors, and how easily can they recover from the errors?
How pleasant is it to use the design? how well errors handled and reported to the user

Why?

Usability is a necessary condition for product success. If a website, app, or service is difficult to use, people will seek alternatives. Current best practices call for spending about 10% of a design project's budget on usability. On average, this will more than double a products desired quality metrics. Usability can also help cut training budgets and increase productivity. Essentially Usability leads to increased sales, registered users, customer leads, or whatever desired goal motivated the design project.

 

What?

There are several methods for studying usability including:

Interview

can be face-to-face or via phone/skype etc. Follows a script and often used to gather stakeholder of specialist feedback
Participatory Design
involves collaberative working with groups of users to generate or critique design ideas and solutions
Usability Test
targeted uses are guided/observed performing key scenarios/tasks to validate & test designs at various stages of development
Card Sorting
method for increasing a system’s findability. Used to help design or evaluate the information architecture. Participants organize & prioritise topics or features
Data Analysis
looking for patterns in quantitative test data such as eye tracking, heat maps, task errors, time or clicks to complete, and physiological (biometric) data to detect emotional response especially with video games user testing