Card sorting is a user experience research method where users organize topics into groups on cards, hence the name card sorting. Using this research technique allows companies to organize the information architecture of a web or mobile application in a way that best aligns with the user’s mental model.
Open card sorting can be conducted by putting 40-80 topics that cover the main website content on index cards. Next, 15-20 test subjects, the optimal number of participants, are told to group the topics that belong together. After, the participants are asked to create names for the groups they created.
Lastly, the users are often requested to explain how they created the groups and the thought process behind their choices. Participants can be further used to break up larger groups into smaller subgroups and vice versa, depending on their organizational choices.
Researchers can choose to use an open card or closed card sorting. The open card implies that users can name the groups they created, while closed card sorting gives users a set of predetermined category names. Participants are asked to organize the cards into those categories.
Depending on the card sorting project’s time and money, professionals can decide to use moderated or unmoderated card sorting and paper vs. digital. Unmoderated and digital card sorting is typically faster and cheaper to conduct.
However, qualitative observations from moderated sessions are missed. These observations can give valuable insight into a user’s reasoning and explanation for their groupings.
Paper sorting’s biggest advantage is that there’s no learning curve for participants and allows users to easily move cards around and start over versus on a computer screen that cannot display all options in a single view.
When conducting these studies, it is important to be aware of potential study biases that occur through biased tests or how user test sessions are facilitated.