Design Principles for Simplification

Overview | Simplicity | Transparency | Effectiveness and Efficiency

In the following, we elaborate the global simplification goals by proposing a number of related "secondary" design principles, which cover the many aspects of simplicity. These principles allow you to focus on certain simplicity aspects and also maintain an overview of the requirements, which are often in conflict with each other.

Note that some of these principles are direct requirements of the ISO norm 9241 part 10 for software usability.

If you are in a hurry, you can browse through the short descriptions of the principles presented on this page, and then jump directly to section 4 "Tips and Tricks." There you will find a selection of design questions and practical examples regarding simplicity.



Below, we briefly present each principle and assign it to a single global aspect, although the principles often serve more than one goal. In the following sections, we will explain how each of these principles fulfills the goal of simplification and demonstrate how it can be used in the design of applications that are easy and efficient to use.


Reduction Reduction means to reduce an application to its essentials. This principle is applicable to all aspects of application design:
  • Reduce the functionality (goals)
  • Reduce the structural and navigational complexity
  • Reduce the interface (screen) complexity
Organization, Structure Organizing and structuring an application relates to:
  • The general application structure (screens, pages, and so on)
  • The navigational structure
  • The structure of the functionality
  • The screen or page layout
Integration The principle of integration stresses the importance of integrating simple, elementary tasks into a coherent framework.
Prioritizing Prioritizing means that applications should focus on the essential tasks and not try to serve a multitude of, possibly diverse, goals. This includes optimization with respect to the important aspects of a task.
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Understandability Software should be comprehensible for users – not only its creators. There are many aspects to understandability: application structure, navigation, procedures, and terminology. Or more concrete: This principle requires that users always know the state of their task, what to do next, how the application reacts to certain inputs, and so on.
Learnability (ISO) An application should be easy to learn. It should also be easy to relearn, so that casual users can master it.
Self-descriptiveness (ISO) Self-descriptiveness requires that an application can explain itself to the user.
Continuity, Stability An application should provide a stable and familiar working environment for users.
Consistency, Conformity to User Expectations (ISO) An application should be consistent and meet the users' expectations with respect to work practice as well as user interface standards.
Feedback Feedback provides users with clues about the effectiveness of their actions and what is going on in an application.
Metaphors Metaphors, usually taken from the real world, help users to transfer their prior knowledge to new software applications. This facilitates the use of applications, especially for novices and casual users. Metaphors can be also an effective integration tool.
Efficient (Re)presentation Using efficient representations, for instance a graphical representation instead of a textual one, can make an application much easier to understand.
Aesthetic Aesthetic appeal is an important factor, especially on the Web. An aesthetically pleasing design can contribute to the overall simplicity and acceptance of an application.
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Effectiveness and Efficiency

Goal Orientation (ISO) An application has to fulfill certain goals. There are goals dictated by the task at hand, and there are user goals, which may not coincide with the first ones. In the context of simplicity it is important to minimize the number of goals for an application – preferably to one.
Suitability for the Task (ISO) An application is used for performing a certain task. With respect to simplification it should not only enable users to accomplish the task, but should also let them do so in an easy and intuitive way. That is, the application should "fit the task."
Error Robustness (ISO) An application should be permissive to errors, or, preferably, should prevent them.
Distribution of Tasks (Division of Labor) An application accomplishes its goals through the interplay of user and system actions. You as the developer determine how much work load is put on the user and how much work is taken over by the system.
Balance of Controllability vs. Guidance - Amodality vs. Modality (ISO) Controllability is often translated as "the user is in charge, not the computer." Users should at all stages of the processing be able to decide what to do next. With respect to simplification, you have to balance controllability with guidance to achieve an optimal fit for the respective user groups.

Amodality and modality are two important aspects: Amodality means that the application does not force users into predetermined actions. Modality, on the other hand, forces users to perform a certain action.

Parallelism Parallelism has several aspects:
  • Parallel processing of tasks
  • Parallel provision of functionality
  • Parallel provision of information

Typically, it makes applications more efficient, but it also increases complexity.


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Source:  Simplifying for Usability