A well-designed information structure not only guides the user to what they are looking for, but directly affects the perceived usability of a digital product. In a world where every second counts, a confusing navigation system can be very costly in terms of abandonment, frustration and lost conversions. Tree testing, also known as “reverse card sorting”, has established itself as one of the most effective techniques for validating the information structure before designing or redesigning an interface.
This article explores what tree testing is, why it is useful in user experience design, how to implement it correctly and which best practices to follow. For example, imagine having to restructure the navigation of an e-commerce site with hundreds of product categories: how do you know whether users easily find where to click to look for a sweatshirt? Tree testing lets you find out, even before designing the graphical interface.
What is Tree Testing
Tree testing is a quantitative research technique that lets you test the effectiveness of the hierarchical content structure of a site or application, without interference from the graphical interface. Users are shown a simple text list of categories and subcategories (the “tree”) and each of them is asked to identify where they would find a particular piece of information or function.
Unlike card sorting, which is used to build the tree, tree testing is used to validate it, measuring key metrics such as:
- Success rate (percentage of users who find the correct path)
- Time to task completion (average time taken to complete a task)
- Path taken (the route navigated within the tree)
- Directness (whether the user found the answer on the first attempt)
As highlighted by Nielsen Norman Group, tree testing is particularly useful in the early stages of the design process, before investing resources in developing the visual interface.
Why use Tree Testing in a UX project
Tree testing is a powerful tool for validating the clarity of the information architecture. In fact, even an aesthetically pleasing interface can be ineffective if the content is not organized intuitively. The main reasons for including tree testing in an Experience Design project are:
- Identify points of confusion: it shows where users get lost or take wrong shortcuts.
- Validate design decisions: compare alternative versions of the information tree to understand which works best.
- Reduce development costs: testing the structure before the UI avoids having to rework wireframes or code that have already been produced.
- Optimize the cross-channel experience: a good information structure makes navigation consistent across desktop, mobile and app.
A report from Qualtrics confirms that an intuitive information system is one of the top sources of satisfaction at digital touchpoints, improving both engagement and retention.
How to run a Tree Test: phases and tools
Running an effective tree test involves a few essential phases:
1. Defining the information tree
It can be the current structure (to identify problems) or a new proposal (to validate). It is important that the tree has no more than 3-4 hierarchical levels and that category names are consistent and understandable.
2. Choosing the tasks
Tasks must reflect realistic scenarios: “Where would you look for your account settings?” or “Where would you find information about returning a product?”. Ideally you test between 5 and 10 tasks per session.
3. Selecting the target
Participants should represent the end users of the service. To get reliable results, 30 to 50 users per tested version are enough.
4. Analyzing the results
The value of tree testing lies in analyzing the key metrics: task completion success, the paths taken, the clarity of labels. The goal is to identify recurring patterns that signal the need for intervention.
5. Iteration
Once the problems are identified, you can modify the tree and test again. This iterative approach, typical of design thinking, lets you arrive at a truly user-centered structure.
Among the most popular tools for running tree tests are:
- Optimal Workshop (Treejack): probably the best known, it makes it easy to create information trees and analyze users’ paths in detail.
- Maze: ideal for agile teams, it lets you integrate tree testing into broader remote user testing flows.
- UXtweak: an all-in-one tool that includes both tree testing and card sorting, with advanced analysis features.
- UsabilityHub: simple and intuitive, suited to quick tests with large samples.
Tree Testing vs Card Sorting: differences and complementarity
Many professionals confuse tree testing and card sorting, but the two techniques serve different purposes and are often used together:
- Card Sorting: exploratory, used to build the structure, starting from users’ perception of how to organize content.
- Tree Testing: validating, used to check whether the hypothesized structure really lets users find information.
As Interaction Design Foundation also explains, tree testing is one of the most reliable tools for optimizing information architecture when starting from insights that have already emerged from card sorting.
Best practices for effective Tree Testing
A poorly designed test can produce misleading data. For example, proposing an information tree with overly generic entries such as “Services”, “Information” or “Misc” can confuse the user, making it hard to identify the correct category. In a study run by NN/g, similar structures led to an error rate above 40% in the assigned tasks. Here are some good practices to follow:
- Use descriptive, realistic labels
- Avoid ambiguity or duplicates between categories
- Do not include graphic elements or clickable links: the aim is to test the structure only
- Balance the length of the tree with the length of the session
- Analyze the wrong paths, not just the successes
At Then, we use tree testing to support both complex redesigns and targeted usability optimization work, especially on portals with an articulated hierarchical structure (e.g. e-commerce, intranets, knowledge bases). This lets us intervene surgically, drastically improving navigability and reducing users’ cognitive load.
When to use Tree Testing: typical use cases
Tree testing is particularly useful in contexts such as:
- Redesign of sites with many sections and subsections (e.g. corporate sites, e-commerce, public portals)
- Validation of mobile navigation (where space limits accentuate information problems)
- Content migration (e.g. from a CMS to a new system)
- Checking of naming and labeling before the wireframing phase
It is also an excellent way to support decision-making workshops, bringing objective data into the discussion among internal stakeholders.
Common mistakes to avoid
- Testing too many tasks in one session: beyond 10 you risk fatigue and a drop in data quality
- Ignoring the measurement of wrong paths: even failures are valuable insights
- Involving an irrelevant sample: without target users the data is not reliable
- Neglecting iteration: a single test cycle is not enough
Conclusion
Tree testing is a simple but extremely powerful technique for improving UX at an early stage. It lets you validate hypotheses, discover pain points and optimize the organization of content before reaching the visual phase. Integrating it into a UX process means designing information structures based not on assumptions but on concrete data, reducing errors and waste.
In a landscape where user experience is increasingly a decisive competitive factor, techniques like tree testing are a strategic investment, able to make the difference between a usable product and one that is truly centered on people.
If you are facing a redesign of your site or have doubts about how your content is organized, consider including tree testing in your process. The Then team is available to structure and run tailored tests, with UX Research experts and professional tools. Find out more in the section dedicated to User Experience or contact us at info@then.agency.
