An introduction to card sorting

Confidently define your information architecture with card sorting.

Introduction

When you design your website or app well, your audience will easily find what they’re looking for. If you found your way to this guide, we know you already have that front of mind. But how can you validate whether the way you intend to organize your content makes sense to your target audience?

Card sorting is a useful technique in information architecture (IA). You can use it to understand how users think about your content and to help you make confident decisions about how to organize it.

In this guide, we’ll explore what card sorting is, along with the different card sorting methods. We’ll also share advice and top tips on how to run a remote card sort test and how to organize and analyze your data.

What is card sorting?

Card sorting is a well-established user experience (UX) research method where participants group topics into categories according to criteria that makes the most sense to them. 

It’s often used to help inform the IA of a site or app. By giving your participants labeled cards to sort, you can gain useful insights into how and why they group content in certain ways. And creating an IA that’s intuitive is essential to providing a positive user experience. 

The observations you can gain through card sorting can also help you identify trends and decide how to categorize your content in ways that align with the mental model of your participants. 

There are three types of card sorting techniques:

  • Open card sort: Participants sort cards into categories that they determine, and label each category themselves.
  • Closed card sort: Participants sort cards into predefined categories.
  • Hybrid card sort: Participants sort cards into predefined categories, and can also create their own categories.

We’ll dig into these techniques in more detail below.

You can run a card sorting session in person using physical cards, or remotely using online tools like UsabilityHub. In this guide, we’ll largely be focusing on the latter.

What is card sorting used for?

Card sorting is beneficial when you want to understand how to:

  • Sort items into categories, typically website pages or product offerings.
  • Choose helpful labels for those categories.

Say you’re creating an e-commerce furniture site. Would your customers expect to see desks, office chairs, and shelving listed as separate categories? Or are they more likely to navigate to ‘home office’? How would readers of your food blog expect to see recipes sorted – by meal type, course, cuisine, diet, season, and ingredient?

You might use card sorting when you want to:

  • Make an informed decision about the IA of your site or app. You can use card sorting when building a new site, or improving or adding a new section to your existing site. By asking your target audience to arrange items, you can discover how people understand different concepts.
  • Quickly gain research insights. Remote card tests are affordable, simple to create, and easy to recruit and share with participants. Online card sorting tools have reporting capabilities built in, so you can view, sort, and analyze data quickly.
  • Discover the mental model of your target users. A mental model is what users know about a system, like your website. Card sorting can offer useful insights into the perspective of your users. For example, how they would prioritize new features or how they would name something. 

Types of card sorting

Let’s explore open, closed, and hybrid card sorting in more detail, and some of the use cases for each method.

Open card sorting

In an open card sort, you create a list of cards and ask participants to define and label categories to sort them into. The participants are free to create any categories they like, and might choose to differentiate the cards in a range of different ways.

Open card sorting uses a generative research method, which means that it aims to gain a deep understanding of your users and their experiences in order to create solutions or innovations for them. It’sgenerally used when creating a new IA from scratch, or improving the IA of an existing site or app. 

You might use this method to get ideas for:

  • Organizing products in your ecommerce store.
  • Categorizing content on your blog or learning site.
  • Organizing products, features, and solutions for your SaaS site.
  • Categorizing booking options on a travel site.
  • Structuring help center documentation.

Closed card sorting

Closed card sorting uses an evaluative research method, which means that data is collected to evaluate a product or problem and inform the solution.

In a closed card sort, you create a group of cards and ask participants to sort them into predefined categories.

Closed card sorting won’t show you how participants conceptualize categories, but it will help you evaluate how well an existing category structure supports content from their perspective. For this reason, closed card sorts are used when you want to add new content to your existing site, or gain further insights after an open card sort. 

You might use this method to:

  • Validate whether participants understand how you’ve categorized content.
  • Highlight unclear or misleading category labels.
  • Prioritize and rank features and products based on set criteria.
  • Define a value proposition (e.g. by asking your customers what matters most to them using criteria like must have/should have/nice to have).

Hybrid card sorting

As the name suggests, hybrid card sorting is a mix of open and closed card sorting methods. Participants can create and label new categories and organize cards into predefined categories.

Hybrid card sorting is beneficial when you want to gain new insights into how your audience sorts content and validate how content is organized. It’s a useful method when adding new content to an existing information architecture.

Moderated and in-person card sorting 

A moderated card sorting session involves a moderator conducting and overseeing the activity. Moderators brief participants at the start of the session and ask them follow-up questions at the end to gain qualitative insights. 

Moderated sessions are commonly run in person and can be conducted in a group or one-on-one setting. Topics are written on physical cards and participants organize those cards into groups. The advantage here is that the process is simple and flexible. Participants can sort and move physical cards around into categories, or even start over. The downside is that, as the researcher, you have to manually document each category.

Besides asking questions, the moderator might also ask participants to express their thought process aloud as they go, to gain further insights. You might therefore opt for a moderated session when you want to gain a deep understanding of how your audience thinks.

Unmoderated and remote card sorting

An unmoderated card sorting session involves participants working on their own and without a moderator. They’re usually run remotely online using a digital card sorting tool, where participants can drag-and-drop cards into groups.

Remote unmoderated card sorts require fewer resources, so are generally quicker, easier, and less expensive to organize than an in-person moderated session. One benefit of using a card sorting tool is that it analyzes the results for you, so you can see at a glance which items are commonly grouped together, along with the most common category names.

While you don’t have the benefit of asking participants to explain their thought process, most online tools have the functionality to ask participants follow-up questions.

You might run an unmoderated remote card sort when you:

  • Are working with limited resources and budget.
  • Want to gain insights from a large group of participants.
  • Want to gain insights from participants with different demographics, e.g. from people in different countries.

How to choose a card sorting method

When figuring out which card sorting method to use, it’s worth considering what stage your project is at. If you’re in the early concept stages of a website build, open card sorting might be beneficial. Closed card sorting might be the way to go if you’re further along and want to validate a concept.

Open and closed card sorts can also complement each other. For example, you can use an open card sort to define candidate sets of categories and follow this with a closed card sort to identify which set of categories performs best.

Resources, your research goals, and the specifics of your project will no doubt also affect your decision.

How to run a remote card sorting test

Before beginning your card sort test, take some time to establish your research goals and choose a set of test topics based on your goals. Once you’ve got that set, you can use the below steps as a guide to running your test remotely. 

Create the cards and categories

Begin by brainstorming your cards and categories. Pull together all the information you can, like your sitemap or product inventory list. You might even find it beneficial to run a content audit on your site to get a full list of your existing content. You could also ask for input from stakeholders and review how similar organizations or competitors organize content. 

Write down all the items or concepts that represent the main information on your site. For example, if you want to find out how participants group categories for an electrical/home appliances ecommerce store, you might list out the following as separate items: laptop, monitor, keyboard, webcam, DSLR camera, camera bag, microwave, kettle. You can then refine your list until you’re left with the most relevant items. Write one concept per card to make information clear to your participants.

If you’re running a closed card sort, you’ll also need to create the categories for participants to sort the cards into. Using the above example, you might include ‘Computers & Accessories’, ‘Cameras & Accessories’, and ‘Appliances’.

The number of cards you create will depend on your project. For an open card sort, 30–50 cards should allow you to gain useful data about how your audience categorizes the cards (but it might be worth limiting the number of cards shown to each participant – more on this below). If you’re running a closed card sort with simple grouping options, you might choose to go higher than this.

Build the card sort test

At the start of your test, be sure to include a welcome message and share your research goals. When using a tool like UsabilityHub, detailed instructions on how to take the test are built in, but you can also provide custom steps for your participants. We have detailed step-by-step instructions on how to create an open sort task and a closed sort task in our help center.

As mentioned in the section above, you might also choose to ask participants additional follow-up questions. For example, asking participants whether they found the test easy or difficult. 

You might also ask further questions to those participants who found the test difficult (e.g. asking which cards were difficult to sort or which categories were difficult to name). In the UsabilityHub test builder you can apply these conditions using test logic.

Recruit participants 

One of the primary goals of card sorting is to gain insights into how the people you’re designing for think, so we recommend recruiting participants that represent the demographics of your intended audience.

If you’re testing an internal product, you might recruit employees or share with an external test group of key customers. Depending on your organization, you might invite customers via social media, in-app messages, or a mailing list. If you’re going down this route, an incentivization (like a discount to your product) may help to recruit more responses.

A recruitment panel – like UsabilityHub’s user research panel – can be a quick and easy option, especially if you’re looking for a large testing group or participants with specific demographics.

How to sort and analyze remote card sorting data

Once all of your card sort results are in, it’s time to sort and analyze the data. These results can be:

  • Qualitative: The responses participants give to follow-up questions and the categories they define and label.
  • Quantitative: Which cards appeared together most often, and how often cards appeared in specific categories.

Most remote card sorting tools will include built-in reporting to help you sort and analyze your results. Begin by reviewing the results at a high level. Try to find common patterns in how the cards are sorted and (for open card sorts) the category names that are provided.

If you conducted an open card sort, take some time to review and standardize categories with similar labels – look for different spellings, capitalizations, and wording. Be sure to look at both the category label and the cards in each category to make sure your participants are thinking similarly.

On UsabilityHub, an agreement matrix shows the percentage of participants that placed each card into a category. And for open card sorts, a similarity matrix shows how often pairs of cards are sorted into the same category, regardless of which specific category they were sorted into.

When reviewing your data, look for clear clusters. How frequently are cards placed in certain categories? Are there any outliers? Identify cards that are spread across multiple categories. This will help you to identify the different mental models of your participants, for example, participants who sorted household products by type versus by room.

After running an open card sort, define a list of categories based on your observations and validate these results with a closed card sort.

By now you should have valuable insights to share with your team about your target audience, and can make confident decisions about structuring the content on your site.

Top tips for card sorting

Here are some top tips and best practices to consider when running a card sort.

  • Limit the number of cards shown to participants. While the UsabilityHub test builder supports a maximum of 100 cards and 30 categories, we recommend showing around 30–40 cards per participant. In the test builder you can set limits, for example show 25 out of 50 cards, and our system balances the number of times each card is displayed. This helps keep the task manageable for your participants while still allowing many cards in your study to be sorted. 
  • Choose card text carefully and avoid bias. Jakob Nielsen from the Nielsen Norman Group advises against using terms that contain the same words, as participants tend to group these cards together. For example, most participants will group ‘Strawberry planting’ and ‘Strawberry growing’ together, because ‘Strawberry’ is repeated. Likewise, ‘Planting strawberries’ and ‘Planting wheat’ are likely to be grouped together because ‘Planting’ is repeated. 
  • Make sure each card is easy to comprehend and represents a single concept. The information you provide on each card needs to be clear. If your participants don’t understand the meaning, you’re likely to end up with inconsistent categories. The same applies for category labels in closed card sorts.
  • Make sure each card represents a concept that can be grouped. For example, listing different modes of transportation and including a card that says ‘transport’ will no doubt confuse your participants.
  • Add images. Images can be a good way to illustrate concepts or items, or help to clarify text.

Frequently asked questions about card sorting

What is card sorting?

Card sorting is a well-established user experience (UX) research method where participants group topics into categories according to criteria that makes the most sense to them. It’s often used to help inform the IA of a site or app. By giving your participants labeled cards to sort, you can gain useful insights into how and why they group content in certain ways.

What are the different card sorting methods?

There are three types of card sorting methods. In an open card sort, participants sort cards into categories that they determine, and label each category themselves. In a closed card sort, participants sort cards into predefined categories. In a hybrid card sort, participants sort cards into predefined categories, and can also create their own categories.

What is card sorting used for?

Card sorting is generally used to define navigation structures, organize product categories, and build content taxonomies.

Is card sorting qualitative or quantitative?

Card sorting data – for example, which cards appeared together most often, and how often cards appeared in specific categories – is quantitative. The responses participants give to follow-up questions is qualitative.