First of all, I would like to say that I don’t consider myself to be an expert in usability testing and user interface design. But I want to share my knowledge and quite unpretending experience in these areas with others. That is why I’ve decided to write a series of articles about usability and usability testing. Maybe, somebody (or many) of you already know this information.
At the beginning I’ll tell you about history of usability, guidelines and standards of usability, definition and components of the concept of usability.So, let’s start.
What is usability?
Nowadays the software market is sated enough. A certain task can be solved by means of tens competing programs with almost identical functionality. Finally, the choice of this or that application more and more depends on nonfunctional characteristics. The user interface which provides simplicity and overall performance with a software product, can be of primary importance for making such a decision.
High-quality user interfaces have approximately 70 % of desktop applications and about 40 % of applications for mobile devices. In other words, software developers are concentrated on implementation of the functional requirements, but user interfaces are developed in the last queue. Thus, the question about usability costs sharply enough.
For the first time, the term «usability» has been used in 1977 in the scientific work devoted to the analysis of the software, as determination for one of quality factors of a product along with ten others in McCall ‘s model. Later on its basis and a similar Bohm’s prototype, the sample of software solutions quality was published by International Organization for Standardization in 1991 in standard ISO/IEC 9126. In the second half of 80th years there was an application-oriented discipline the usability-engineering devoted to methodology of an estimation of usability. In 1998 standard ISO 9241-11, actual at present, has been published. This basic standard defines the term “usability” and describes the determinations connected to it. It expands the general principles of usability, and also contains specific recommendations.
In addition, there are a number of guidelines and standards providing a set of recommendations for developing and testing of user interfaces. Here are some of them:
Section 508 standard – Web-based Intranet and Internet Information and Applications (Rehabilitation Act, § 1194.22). Methods of creation of static and dynamic web pages are described here.
Microsoft Developer Network Recommendations (MSDN). In MSDN it is possible to familiarize with rules of creation of the user interface according to Microsoft ideology (both for Microsoft Windows and for Pocket PC / Windows Mobile platforms). So, according to standard ISO 9241-11, usability is a science, defining the level of efficiency, satisfaction and effectiveness with which the product can be applied by users in specific conditions for achievement of the given purposes.
Usability is the complex concept including following elements:
Effectiveness — completeness and accuracy of user goals. It is estimated by an amount of the errors made by users, and also by means of a share of correctly fulfilled jobs.
Efficiency — relation of expended resources to effectiveness. It is measured by task runtime, cognitive load, duration of training and complexity of performed activity.
Satisfaction — perception of a product by users and comfort of its usage. To determine this parameter, questionnaire methodology is used during or after the usability test.
What is usability in composition and what it gives to the user?
Usability is a set of attributes, relevant to the individual evaluation of a product by users and to efforts spent on its use, that can be evaluated by using the following parameters:
- Understandability, or simplicity of understanding of the logic put in a product.
- Learnability, or simplicity of training to its usage. This point is connected to the previous one. Simplicity and intuitive clearness of the interface gives the chance of fast training. Nobody likes idea to sit within some hours to learn and remember the same operation. If there is other program which yields identical result and can be mastered at the first attempt, the user will prefer this more simple and convenient system.
- Operability, or simplicity of operating. Simplicity and reasonableness of control items, the menu, dialog boxes, hot keys and so on providing high speed of operation with the program. Because of it the program can be used with minimum expenses of time and efforts of consumption. For example, in business applications that means a higher performance of users’ work.
- Attractiveness. The interface is considered useful if it is esthetically attractive and gives satisfaction at product usage. If the product isn’t considered esthetically attractive, actual and unusual (it is finite, it depends on the specified context of usage and isn’t identical to games and a packet of office programs), probability of buying it by a user is little. If the software solution hasn’t transited such a face-control and hasn’t been bought, all remaining, including functionality, simply loses its significance.
- Compliance, or correspondence to official branch standards and the standard agreements. Acceptance in attention of scientific recommendations will provide small fatigue of the user by operation with the program. Besides, it means extra efficiency of users’ work for a long time. Such an advantage of system is the main principle for many enterprise customers.
- Friendliness and user support (and, as consequence, insignificant errors of the user). This point is tightly connected to the previous one. It is very important in cases like medical systems, a production system and transport control, accounting and analytical business applications, and also many other things where the price for bug fix can be the expensive.
Next time I’ll tell you about definition of usability testing and its methods.