Card sorting is a methodology to test a group of subject matter experts (SMEs) to create and define a hierarchical understanding of information. It is useful for information design, as content creators can use that hierarchy to determine task flow, content navigation, and concept and reference presentation order.
Card sorting gets its name from the low-tech approach of identifying and recording key concepts on physical index cards. Test subjects are asked to arrange these cards based on their understanding of the structure and relationship of the content subject matter. Test subjects are organized as groups or can be tested individually.
Card sorting is particularly useful when there is a large number or diversity of items to organize, or when categories of organization is difficult to determine. Using SMEs to perform the sorting operation relies on experience and “grass-roots” knowledge, instead of applying a top-down approach.
There are several types of card sorting:
- Open: Participants create their own categories, relying on their own experience and industry knowledge to determine the classification.
- Closed: Participants are given a set of categories and are asked to assign cards to those categories.
- Reverse: Also known as tree testing, an existing set of categories and sub-categories is provided, and participants must find the most relevant card for a given task or concept.
- Modified-Delphi: A single participant performs a full card sort, a second participant iterates on the first participant’s model, and subsequent participants continue to iterate on the previous participant’s model.
Results from the analysis of card sorting is used to understand the categories and relationships of the subject matter. This knowledge is used to design better content, and to provide a more intuitive and efficient presentation of information.
Although card sorting is still often performed in its original low-tech format, there are online and automated tools available which offer more widespread accessibility than individual personal interactions.
