Usability

What is Usability?

• The extent to which a product can be used by specified users to achieve specified goals effectively (completely and accurately) and efficiently (fast and with minimum effort) while functioning in a predictable and consistent manner.

• If the usability of a product or service is high, then the product can be considered intuitive, pleasant, satisfying to use and tolerant of user errors (prevents user errors from occurring or makes them easy to recover from).

Usability Objectives

• There are several criteria that need to be met in order to ensure high usability.
• These are usefulness, learnability, likability and effectiveness. They are aimed for when making a design.

Usefulness

• Product enables user to achieve their goals - the tasks that it was designed to carry out and/or wants needs of user.

Learnability

• How easy it is to learn to use a product or how intuitive a product is to use.

Likability

• The perceptions, feelings and opinions about a product by a user.

Effectiveness

• Quantitatively measured by speed of performance or error rate and is tied to a percentage of users.
• How well (or efficienctly) a product enables the users to achieve their goals.

Benefits of High Usability

Higher Product Acceptance

• Product acceptance is the knowledge that a product or service paid for will meet up to its defined expectations.
• Having high usability allows for higher product acceptance, as it will me more effective and pleasant to use.

Positive User Experience

• User experience is a person's perceptions and responses that result from the use or anticipated use of a product, system or service, this can modify over time due to changing usage circumstances.
• High usability allows for positive perception and response of using a product.

Increased Productivity

• Developing products and services with the user in mind so that they can reduce time wasting and simplify complex aspects of the product.
• This allows the user to accomplish their goals easily and with less effort, increasing user productivity.

More Tolerant to User Errors

• User errors are mistakes and slips when using the product due aspects such as complexity or inefficiency.
• Some user errors are inevitable, as people are fallible, therefore it is important that users can recover from their errors.

Reduces Need for Training and Support

• Training and support is the help and guidance on the use of a product, such as tutorials or instructions on how to use the product.
• If the product is usable, training and support can occur naturally or is not necessary, which makes the product more appealing to unfamiliar users.

Consensus

• A design team should be “user” driven and frequent contact with potential users is essential.
• To understand how a product, service or system may be used, the designer must consider the prior knowledge and experience of the users, as well as their typical psychological responses.
• Evaluation methods that utilize appropriate testing and trialing strategies must be used to determine these aspects.