7.2 Usability

7.2 Usability

Usability simply means how easy is the product to use. It is the extent to which a product can be used by specified users to achieve specified goals effectively.

Usability objectives:

Usefulness
product enables user to achieve their goals
- the task that it was designed to carry out and/or wants needs of user.
Effectiveness
ease of use
-quantitatively measured by speed of performance or error rate is tied to a percentage of users.
Learnability
-user's ability to operate the system to some defined level of competence after some predetermined period of training. Also, refers to ability for infrequent users to relearn the system.
Attitude
likability
-user's perceptions, feelings and opinions of the product, usually captured through both written and oral communication.

Benefits of Enhanced usability:

When Enhanced usability increases:

• Product acceptance                                                                                                                                   - The knowledge that a product or service paid for will meet up to its defined                                 specifications. If it says it will do, it will.
• User experience                                                                                                                                         - a person's responses from the use or anticipated use of a product/system/service.                         (brand loyalty and increased sales)
• Productivity                                                                                                                                             - Developing products and services with the user in mind can reduce time wasting or                    difficult to understand aspects of a product. This lead to a more pleasant user                              experience.

When Enhanced usability decreases:

• Reduced user error                                                                                                                                    - with simpler interfaces/controls, user error is reduced/eliminated. Leading to better                      experience and product acceptance through reduced frustration.
• Training and support                                                                                                                               - If a product has a more intuitive user interface, a more pleasant user experience and                   simpler controls, there is less for training and support to the consumer and so, reduced               cost.

Characteristics of good user-product interfaces:

Simplicity and ease of use
Is it simple and easy to use (shazam) cut out all the extra control.

Intuitive
Quickly become competent and work it out, instruction manual poorly made

Low memory burden
Keep it simple but still adding features, users don't have to memorise many features.

Visibility
Controls should be visible, and should be obvious how they work, also should convey correct message (Door with the sign: "push/pull")

Feedback
Provision of information, eg and audible tone as a result of an action. (Opening ketchup bottle produce an audible tone so you know its opened/closed)



Affordance
It is the property of an object that indicates how it can be used.

Mapping
It relates to the correspondence between the layout of the controls and their required action.

Constraints
It limits the way that a product can be used eg. design of an USB device ensures that they are inserted the correct way.

Population stereotypes
we expect a certain actions, such as turning or sliding them in a certain direction (door), also colours red is the colour for asian cultures which means luck.



Pros and cons of using population stereotypes for designers and users.

Pros: 
-Allows assumption and associations about of a group of people. (Designer)
-Make judgement and decisions quickly. (Designer)
-Possibly predict the behaviour or use of a product/system. (Designer&User)
-Users' needs and behaviour can be identified, thus usability considerations are met. (User)


Cons:  
-Assumptions/associations of a particular stereotype may not fit all people of that population. (Designer)
-Judgements/decisions could be wrong. (Designer)
-Not everyone who 'look alike act/think alike', therefore behaviour or way a product was intended to be used may be wrong. (Designer&User)
-Requires a lot of research.