Card Sorting

What is it?

Card sorting is a technique discovering how the users understand, categorize and prioritize information. This method helps understand a user's mental model for organizing information and can help structure information in a way that makes it easy to find.

Why do you do it?

Card sorting can provide insight on how people organize content and information which can help inform the information architecture of an application. Card sorting can be useful in the following scenarios:

Build the overall structure and navigation for your application
Decide what to put on each tab
Organize information in the form of cards or tiles
Label objects such as charts or tiles

When to do it?

It can be used in the Converge and Prototype phase when you are tying to test how to organize newly drawn up concepts. It can also be done during the Undertand phase if you are trying to improve an existing application's Information Architecture of an existing application.

How to do it?

Before the card sorting session begins, the team needs to first produce cards. According to NNgroup, these cards should contain 40–80 items that represent the main content of the application. Write each topic on an individual index card.

These index cards could represent

Names of sections of the application

Names of tiles on a page

Key questions answered by charts

Description of chart objects

Data elements

Measure

Dimension

Measure by Dimension

Ask the user to organizes cards into groups. Shuffle the cards and give them to the participant. Ask the user to look at the cards one at a time and place cards that belong together in one pile.
Categorize or label the piles based on the type of card sort you chose to conduct. Open or hybrid card sorting can be used to to explore all meaningful categories. Closed card-sorting sessions on the other hand can provide more structure and focus to the session. At the end of a closed card sorting session, the lead of the session can still ask participants if they would rephase the categories, or if they would combine certain categories.

Open / Closed / Hybrid Card Sorting

Open card sort: Participants sort cards into categories that make sense to them, and label each category themselves

Closed card sort: Participants sort cards into categories you give them

Hybrid card sort: Participants sort cards into categories you give them, and can create their own categories as well

It is important to remind the user that they can move cards around between groups as they are performing the card sort. They are also not required to categorize/group all cards and it is okay to have a pile of unknown cards.
At the end of a card sorting session you may talk to the user to try and understand their rationale behind grouping cards together.
Repeat this process for about 15-20 users and then analyze the results.
Analyze the results from card sorts to see common categories across participants. This article from UXMatters offers actionable tips on analyzing and using results from card sorting.