Editing Usability (section)

==Designing for usability==
{{see also|Usability engineering}}

Any system or device designed for use by people should be easy to use, easy to learn, easy to remember (the instructions), and helpful to users. John Gould and Clayton Lewis recommend that designers striving for usability follow these three design principles<ref name="Gould, J.D. 1985">Gould, J.D., Lewis, C.: "Designing for Usability: Key Principles and What Designers Think", ''Communications of the ACM'', March 1985, 28(3)</ref>

* Early focus on [[end user]]s and the tasks they need the system/device to do
* Empirical measurement using quantitative or qualitative measures
* Iterative design, in which the designers work in a series of stages, improving the design each time

===Early focus on users and tasks===
The design team should be user-driven and it should be in direct contact with potential users. Several [[#Evaluation methods|evaluation methods]], including [[persona]]s, [[cognitive modeling]], inspection, inquiry, [[prototyping]], and testing methods may contribute to understanding potential users and their perceptions of how well the product or process works. Usability considerations, such as who the users are and their experience with similar systems must be examined. As part of understanding users, this knowledge must "...be played against the tasks that the users will be expected to perform."<ref name="Gould, J.D. 1985"/> This includes the analysis of what tasks the users will perform, which are most important, and what decisions the users will make while using your system. Designers must understand how cognitive and emotional characteristics of users will relate to a proposed system. One way to stress the importance of these issues in the designers' minds is to use personas, which are made-up representative users. See below for further discussion of personas. Another more expensive but more insightful method is to have a panel of potential users work closely with the design team from the early stages.<ref name="pages.cpsc.ucalgary.ca">[http://pages.cpsc.ucalgary.ca/~saul/wiki/uploads/HCIPapers/gould-howto-2-pageperside-ocr.pdf]  {{webarchive |url=https://web.archive.org/web/20101127084949/http://pages.cpsc.ucalgary.ca/~saul/wiki/uploads/HCIPapers/gould-howto-2-pageperside-ocr.pdf |date=November 27, 2010 }}</ref>

===Empirical measurement===
Test the system early on, and test the system on real users using behavioral measurements. This includes testing the system for both learnability and usability. (See [[#Evaluation methods|Evaluation Methods]]). It is important in this stage to use quantitative usability specifications such as time and errors to complete tasks and number of users to test, as well as examine performance and attitudes of the users testing the system.<ref name="pages.cpsc.ucalgary.ca"/> Finally, "reviewing or demonstrating" a system before the user tests it can result in misleading results. The emphasis of empirical measurement is on measurement, both informal and formal, which can be carried out through a variety of [[#Evaluation methods|evaluation methods]].<ref name="Gould, J.D. 1985"/>

===Iterative design===
[[Iterative design]] is a design methodology based on a cyclic process of prototyping, testing, analyzing, and refining a product or process. Based on the results of testing the most recent iteration of a design, changes and refinements are made. This process is intended to ultimately improve the quality and functionality of a design. In iterative design, interaction with the designed system is used as a form of research for informing and evolving a project, as successive versions, or iterations of a design are implemented. The key requirements for Iterative Design are: identification of required changes, an ability to make changes, and a willingness to make changes. When a problem is encountered, there is no set method to determine the correct solution. Rather, there are empirical methods that can be used during system development or after the system is delivered, usually a more inopportune time. Ultimately, iterative design works towards meeting goals such as making the system user friendly, easy to use, easy to operate, simple, etc.<ref name="pages.cpsc.ucalgary.ca"/>