Card Sorting

Definition

Card sorting is a simple technique in user experience design and usability testing where a group of subject experts or "users", however inexperienced with design, are guided to generate a category tree or folksonomy.

Card sorting has a characteristically low-tech approach. The concepts are first identified and written onto simple index cards or Post-it notes. The user group then arranges these to represent the groups or structures they are familiar with.

Groups may either be organised as collaborative groups (focus groups) or as repeated individual sorts.

A card sort is commonly undertaken when designing a navigation structure for an environment that offers an interesting variety of content and functionality, such as a web site.In that context, the items to be organized are those that are significant in the environment. The way that the items are organized should make sense to the target audience and cannot be determined from first principles.

Card sorting is applied when:

• The variety in the items to be organized is so great that no existing taxonomy is accepted as organizing the items.
• The similarities among the items make them difficult to divide clearly into categories.
• Members of the audience that uses the environment may differ significantly in how they view the similarities among items and the appropriate groupings of items.

Basic methodology

To perform a card sort

1. A person representative of the audience is given a set of index cards with terms already written on them.
2. This person puts the terms into logical groupings, and finds a category name for each grouping.
3. This process is repeated across a population of test subjects.
4. The results are later analyzed to reveal patterns.

The following are some of the tools that can help you do card-sorting studies.

	OptimalSort	A web-based service. One of several UX-related tools developed by Optimal Usability, a consulting company in New Zealand. Includes a variety of analysis features. Free version allows for up to 10 participants per project, 30 cards per project, and 3 projects. Licenses available for unlimited use. Also see the free tool for analysis of OptimalSort data by Aapo Puskala.
	UserZoom	A web-based service. One of several UX-related tools provided by UserZoom. Supports up to 100 items to sort and up to 12 categories. Supports both open and closed card-sorts. Analysis tools include an interactive dendogram.
	uzCardSort	Runs on Windows, Macintosh, and Linux versions of Mozilla. Provides basic browsing of the data. All data is saved in XML files. Open Source.
	WebSort	A web-based service. Supports sorting of images as well as textual cards. Developed by Larry and Jed Wood of Parallax LLC. Provides a variety of data analysis options. Free version supports one study with 10 participants. Licenses available for unlimited use.
	xSort	A Macintosh application. Developed by EnoughPepper, a company in Lisbon, Portugal. Provides a variety of reports and analysis tools, including hierarchical cluster analysis. Free.
	UsabiliTest Card-Sorting	A web-based service. Provides online data analysis and visualization features, including hierarchical cluster analysis. Provides a free 3-day trial, or unlimited-use paid subscriptions for one month or one year.
	Simple Card Sort	A web-based service. Supports open, closed, and hybrid card-sorts. Provides online data analysis. Provides a free demo account or unlimited-use paid subscriptions for one month or one year.

A video explaining the benefits of usability testing: