Lately I discussed with my Informatics teacher the use of a application (both website and desktop applications) by the end-user, the so called: usability. Usability is the knowledge to design a application so that the user does what you want him to do without explaining it.
When you know the rules of Usability, the application you will (let) build will be far more useful to the end-user and by this save you money (managers: pay a little attention now, this will be interesting :-P ).
The document ISO 9126 (1991) Software Engineering Product Quality, issued by the International Organization for Standardization, defines usability as:
- A set of attributes that bear on the effort needed for use, and on the individual assessment of such use, by a stated or implied set of users.
The document ISO 9241-11 (1998) Guidance on Usability, also issued by the International Organization for Standardization, defines usability as:
- The extent to which a product can be used by specified users to achieve specified goals with effectiveness, efficiency and satisfaction in a specified context of use.
Yeah, this makes it a lot more clear, not. So now in normal English, the definition of usability: the perception of a target user of the effectiveness (fit for purpose) and efficiency (work or time required to use) of the Interface.
It’s usable” or “it’s user friendly” are phrases that are used without too much thought as to the detailed nature of Usability K Tara Smith proposed five technical distinctions between uses of the term. He proposed in his work that this distinction helps in the identification and specification of systems in terms of their non-functional requirements.
Usability 1 = Utility - the thing can be used to complete the desired task. E.g. Digging an allotment with a spoon
Usability 2 = Goal / Task support - the thing is designed to help you complete your task.
Usability 3 = Accommodation – the thing is designed to accommodate different user populations
Usability 4 = Adoption – the thing exhibits significantly more usability than its competitor designs – and therefore will be adopted by users
Usability 5 = Extensibility/ Adaptability – the thing has features that allow it to be adapted or extended to suit a new (unpredicted) task or goal.
Usability consultant Jakob Nielsen and computer science professor Ben Shneiderman have written (separately) about a framework of system acceptability, where usability is a part of “usefulness” and is composed of:
- Learnability (e.g. intuitive navigation)
- Efficiency of use
- Memorability
- Few and non-catastrophic errors
- Subjective satisfaction
But how do you know your design is good enough for the user, how do you know you use usability? In order to do that you have to consider the follow:
- Who are the users, what do they know, and what can they learn?
- What do users want or need to do?
- What is the general background of the users?
- What is the context in which the user is working?
- What has to be left to the machine?
- Can users easily accomplish their intended tasks? For example, can users accomplish intended tasks at their intended speed?
- How much training do users need?
- What documentation or other supporting materials are available to help the user? Can users find the solutions they seek in these materials?
- What and how many errors do users make when interacting with the product?
- Can the user recover from errors? What do users have to do to recover from errors? Does the product help users recover from errors? For example, does software present comprehensible, informative, non-threatening error messages?
- Are there provisions for meeting the special needs of users with disabilities? (accessibility)
So stick to the rules and remember: the end user doesn’t do anything wrong, the programmer does.
Pakku
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