Introduction to usability and testing methods

The word "usability" first appeared in the 1382, and it was applied in the "Blackwell Magazine" (Blackwell ' S-magazine), which was published about 1842 years ago, as it was used to approximate the present meaning. In the 80-90-year period of the 20th century, the technical terminology of product design experienced a shift from "functional" to "usability" to "usability engineering" to "user-centric design". By 21st century, the phrase "user experience Engineering" began to appear in the recruitment advertisements. Traditional usability includes easy learning habits and efficiency, distinguished peers such as Patrick Jordan and Don Norman began to encourage usability practitioners to jump out of the traditional usability spotlight and focus on various aspects of the user's perspective, such as aesthetics, collaboration, accessibility, credibility, Persuasion and pleasure.

Usability

Usability is an important indicator of product quality, from the user's point of view to determine the product's effectiveness, learning, memory, use efficiency, fault tolerance and satisfactory degree. The concept of usability from the 1980s with the development of computer technology by the human Engineering (Human MX UB or ergonomics) field, human-engineering mainly research people in some kind of work environment, anatomy, physiology and psychology of various factors Study the interaction between people and machines and the environment, and study how to unify the work efficiency, the health, safety and comfort of people in working, family life and leisure.

Definitions and concepts of usability are also evolving. The definition of usability in ISO 9241, part 11 of 1983, refers to the size of the effectiveness, efficiency, and satisfaction of a particular user using a product to achieve a specific goal in a particular use scenario. Effectiveness (effectiveness): The user achieves a specific goal of the correct degree and completion, efficiency (efficiency): When the user in a certain degree of accuracy and completion of a specific target consumption of the associated resources, Satisfaction (Satisfaction): The use of product comfort and acceptability. This definition emphasizes the use of a product by a particular user in a particular target and context.

As usability continues to be applied and developed in practice, the usability concept shifts to more operational and specific parameter metrics and design principles. Shneiderman in the 1980s, with the development experience and good usability case, the general application of user interface design eight interactive design principles, is still considered by developers as the highest principle of usability design and widely used At the same time, the GOMs (Goals-operations-methods-selection rules) model presented by card and others provides a way to quantify usability and introduces usability research from experimental psychology to cognitive psychology. Lund introduced a more detailed usability principle in the 90 's, these 20 principles have always emphasized the importance of users in the usability concept, requiring developers to have a thorough understanding of user needs, backgrounds, and evaluations; Apple of the same age, incorporating usability concepts into HMI design guidelines, To guide the design and development of graphical interface system. After that, usability research focuses on a number of factors that affect usability, including user backgrounds, task settings, environmental conditions, user sentiment, test methods for usability, and more.

A summary of usability includes 4 features:

First, usability is both a quality parameter used to assess the user interface and product availability (Ease-of-use) and a way to improve the overall quality of the product in the design process. User requirements for different products are not the same, usability needs to change according to different products, and as a way to improve the quality refers to the availability of some research tools, such as user testing and expert evaluation, etc.

Second, usability is closely related to the function of the user using the product, the purpose of the user's function is different, then usability becomes the criterion of whether it meets the user's purpose and satisfies the needs of the user's behavior and cognition.

Third, usability is concerned with the process by which a particular user satisfies a specific purpose in a particular scenario, which reflects that usability is not fixed, but that it needs to be flexibly changed according to specific products, users, and circumstances.

Four, usability throughout the product cycle, in order to ensure product availability, at the beginning of the product design should be considered and put into the availability of work, for the existing products, similar products testing evaluation, or the use of prototype methods for testing and evaluation, improve the new design.

Usability testing and methods

The most important way to enhance usability is to adopt iterative design (iterative), through repeated evaluation of the product prophase development phase, to continuously obtain user feedback, and then modify and optimize the product design until the acceptable availability level is reached. The assessment process is the process of conducting usability testing, which is the process of selecting different methods to test the quality of the product. It aims to establish evaluation criteria, identify as many usability issues as possible, and guide the design and improvement of the product interface.

In the development process, common usability testing methods include user-oriented testing and expert-oriented testing. User-focused testing includes user testing and sound thinking (think aloud), expert testing with cognitive preview (cognitive walkthrough) and exploratory Evaluation (heuristic evaluation).

1 User Testing
User testing method is the tester requires the user to complete a set of tasks, the user in the operation of the process of problems and errors will be the test personnel records, at the end of the task of questions and error points to cross-examine, so as to quickly find and judge the deficiencies in the product, and then modify. The products used in the test can be finalized or can be incomplete products based on different fidelity prototypes. The purpose of this method is to avoid the risk by taking part in the design test, predicting the possible problems of the final product in the product design stage. The advantage of adopting user testing is that the objective feedback results of specific users can be obtained under certain task conditions to meet the requirements of usability testing.

2 Sound Thinking
The use of sound thinking in the usability testing process and in the field of psychology and sociology is an effective way to obtain user data feedback. Originally proposed by Lewis at IBM, it was further amended by Ericsson and Simon. This approach requires the user to dictate what they see, think, and feel when completing a series of tasks set by the tester, to help observe that the tester can get first-hand feedback from the final discovery of the problem. Observe the tester in the entire testing process is required, objectively and comprehensively record the user said every word, can not interrupt the user's action and expression. The purpose of this method is to identify "who" in the completion of specific tasks, what the "problem", highlighting specific users and specific issues.

3 Cognitive Rehearsal
The cognitive rehearsal method, originally proposed by Wharton and others in the early 90, was optimized by Spencer in 2000 to adapt to the requirements of software development. The method divides the user's action process (purpose, plan, implementation, evaluation) and system feedback according to the task process, and then the experts (designers and developers) conduct a series of review evaluations of each step to determine possible usability problems.

This method is widely used in the early development phase because it can exploit usability problems with low cost and efficiency. However, because it is the expert to judge the behavior of the user, and the experts and users are fundamentally different, which led to the experts and the real user perceived usability problems are different, and the difference between experts is also large, the general discovery of usability problems only 20%~30% is consistent, This also makes the results of cognitive rehearsal methods have some limitations.

4 Exploratory evaluation
In the 1990 project collaboration, Nielsen and Molich The exploratory evaluation method, which is a unstructured usability research approach that evaluates problems in the user interface, based on usability principles, by developers and industry experts, without the need to set tasks and scenarios. Experts complete the assessment based on experience and usability principles.

Although exploratory evaluation can find most usability problems in a very short time, but the method is also challenged by the influence of the experts ' background knowledge, viewpoint experience and so on, the results obtained by the expert evaluation are different from those obtained by the user test, and the reliability is not high.

Source: http://www.baiduux.com/blog/2010/04/06/Usability and test methods