Card Sorting: Understand Your Users For Better Information Architecture

Aug 21, 2020 | UX Guide, User Research

Have you ever been on a website where you’re looking for something, you click on a category but it’s not there, so you try a different category. Nope, still can’t find it. Most people will give up and leave if they visit a site and can’t find what they are looking for. This is why card sorting is important, it helps your users find what they want and easily navigate through your website, this is especially important if you have a complex information architecture.

What is Information Architecture (IA)?

Information architecture focuses on the organization, structure and the labelling of content in an effective way so that users can find information and complete their task easily. The best way to figure out the information architecture is to involve your users in the planning stage by conducting a user research method: Card Sorting.

What is Card Sorting?

Card sorting is a UX research method to derive users’ perception of information space. This is done by recruiting a group of people, that are reflective of your target users, to arrange individual labels according to groupings or a criteria that makes sense to them. They can be asked to label these groups as well. By doing this, we can discover how your target users’ domain knowledge is structured, and an information architecture that meets your users’ expectations is created as an end result. For example: You’re designing a car-rental website, and there’s an offering of about 100 cars for customers to choose from. How would you best organize all the vehicles into suitable categories for customers to easily browse and find what they are looking for? Technical terms such as family car, full-size luxury car, executive car for categories may not make sense to your users, and they may not be able to differentiate between these categories. The best way to find out what terms and categories makes the most sense to your customers is to conduct card sorting: ask your customers to organize the vehicles into groupings that make sense to them and see how the patterns emerge.

How to Conduct Open Card Sorting

1. Choose a set of topics: There should be 40-80 items that represent the main content on the site, each topic should have its own individual index card. Note: Do take care to avoid topics that contain the same words as the users will tend to group them together. 2. Organize topics into groups: Shuffle the index cards to remove any possible bias and give them to the user. Ask the user to look at the index cards one at a time and to organize the cards together in groups that make sense to them. The piles can vary in size, and if the user isn’t sure where to place a card, it’s okay to leave it to the side in an “unsure” group. Note: Do take care to reassure users that they can change their mind as they go, they can move the index cards from one group to another during the process or even to split off a pile into several new piles. False starts are to be expected since card sorting is a bottom-up process. Pro Tip: Ask users to think out loud during the card sorting process: to speak aloud or verbalize their thoughts. Doing so allows you to understand the user’s thought process better, it provides detailed information and allows the user to take their time to analyze. 3. Label the groups: Once the user is done sorting all the index cards into groups, give them blank cards to write down a name or label for each group they have created. This will help to reveal the user’s mental model of the topic space, and possibly provide new ideas for navigation categories. Note: It’s vital that this step is done only after all the groups are created. If this step is introduced earlier, the user may lock themselves into categories whilst trying to sort the cards into groups. 4. Debrief: Ask the user to explain the rationale behind their thinking and the groups they have created. You may even follow up with questions such as:
  • Were there any items that were especially easy or difficult to place into groups?
  • Were there any cards that you felt belonged to two or more groups?
  • What are your thoughts about the items left in the “unsure” pile?
5. If needed, ask the user to break down large groups or group together small groups: Avoid doing this during steps 1-4, only do this once the user’s preferred grouping has been defined to their liking and after the initial debrief. You may ask the user to break down a large group into smaller groups or even ask them to group small groups into a larger category. 6. Repeat the steps above with 15-20 users: Conducting the card sorting with sufficient users is important in detecting patterns, we recommend at least 15 users to derive enough reliable data. 7. Analyze: Look for common groups, categories, themes and items that were commonly paired together. In analyzing the data, if you notice that there were some items that were repeatedly left off in the “unsure” pile, think about why that is. Perhaps the cards weren’t clear enough or it seemed unrelated, that’s why it’s helpful to ask the user why they have left these items in the “unsure” pile.

Open vs Closed vs Hybrid Card Sorting

Open card sorting is the most common and it follows the steps described above where users are free to assign the group labels for the groupings they have created. Closed card sorting is when a predetermined set of categories are provided to the user, and the user is asked to organize the individual index cards into the predetermined categories. Closed card sorting is useful in evaluating whether an existing category structure supports the content well. However, a drawback is that it isn’t reflective of the users’ mental model.  Instead of closed card sorting, tree testing is a good alternative in evaluating navigation categories. Hybrid card sorting is a combination of open and closed card sorting where the user can start by sorting cards into predetermined categories but have the ability to create their own categories if they want to.

Moderated vs Unmoderated

Moderated card sorting includes the debrief step which provides an opportunity to gain qualitative insights from the user by asking questions, and to investigate for further understanding. Moderated card sorting takes a bit more time and is more costly compared to unmoderated card sorting but it’s a small price to pay for further insights. Unmoderated card sorting doesn’t have any debriefing or a moderator to facilitate. It is faster and cheaper compared to moderated card sorting as the moderator doesn’t need to speak with each individual user but unmoderated card sorting lacks qualitative insights. This form of card sorting is suitable as a supplement to moderated card sorting, for highly distinct audience groups where there are 3 different audience groups with 20 users each, it will be very costly and time-consuming to conduct moderated card sorting with all the users. It would be a good idea to conduct moderated card sorting with 5-10 users of each group followed by unmoderated card sorting for the rest of the users of each group.

Paper vs Digital Card Sorting

The traditional way of card sorting is using paper where topics are written on index cards and these physical index cards are given to users to create groups on a large table. The main advantage of this method is that there’s no learning curve for the user, and it’s also a flexible process where users can move cards around easily. It is also easier to move around physical cards on a large table compared to manipulating multiple objects on a computer screen where everything can’t be seen in a single view. The main disadvantage of paper card sorting is the labour-intensive work where researchers have to manually document the groupings of each user and then input all the data into a tool for further analysis. Digital card sorting is done using a software or web-based tool the simulates the card sorting process, the user can drag and drop the index cards into groups. There is a slight learning curve for this method as some users may not be very tech-savvy. However it’s most convenient for the research team as the software can analyze the results and generate the findings: revealing which items are commonly grouped together by all the users, the category names users created and the likelihood of two items being paired together. The main disadvantage is that technical issues may occur, causing frustration and barriers for users in creating the exact groupings they want. Digital card sorting is often preferred in this time of remote work and remote user research and it also allows you to conduct card sorting with users that would otherwise be geographically unavailable.

Card Sorting Tools

1. UserZoom UserZoom is known for its clean and intuitive user interface however you do need to buy the whole package that includes tree test, click test, survey, basic usability test and more. The card sorting tool has a feature in which you can invite users to your study in multiple ways, and it also allows you to segment your users into demographic groups. UserZoom allows you to invite your own participants or select participants from their database of over 120 million users. Pricing: Available upon request 2. OptimalSort OptimalSort has a simple user interface for users and unlike UserZoom, the card sorting tool is available as a standalone product. Stakeholders can be invited to view the data in the results interface. They have a card sorting demo for you to try for yourself and a free version available for card sorting tests but there’s a limit of 30 cards with 10 responses and 3 sessions per study. Price: Individual plan is $166 USD/month, the team plan pricing varies depending on how many people are in the team. For a team of 3+ seats, the price is $153 USD/month per user. 3. usabiliTEST UsabiliTEST offers a reliable card sorting tools for open, close and hybrid testing, with built-in data and analytics. They allow you to track all the answers the users give and even have a feature to send out automatic reminders to users. They offer a free trial for 48 hours where you can try out the tool without a limit on the number of tests you can do. Price: Premium plan is $24.95 USD/month, pro plan is $224.55 USD for a year 4. Proven By Users  Offering a clean and simple user interface, this card sorting tool allows you to see them in preview before going live. It allows a feature where the user can create card subgroups or duplicate cards easily, and you can segment the users. The research data can be graphically represented in matrics and dendrograms and the data can even be downloaded in CSV format. Price: $39.95 USD for a month, $69.95 USD for 2 months, $399.95 USD for a year. 5. xSort  xSort isn’t available on Windows or Linux, it’s only fully integrated with Mac (Intel and PowerPC-based Macs) and their user interface approach is to visually simulate a real-life table with index cards. It provides a variety of open, closed and hybrid card sorting, and the users can create subgroups. In addition, the statistics are updated in real-time. Price: Free


Card sorting is highly useful in understanding how users think about your content, and in the arrangement of information architecture. It helps companies to organize their content in an effective way that is reflective of the users’ mental models, making it much easier for customers to find the information they want and complete their tasks with ease.

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