Card sorting and tree testing are specialty UX-research methods used to design and evaluate information architecture (IA). Many newcomers to IA often confuse these two methods due to their similar goals of enhancing the site's navigation and content structure.
Card sorting is used to determine how people categorize content, while tree testing evaluates an established navigation structure or can help compare alternative structures.
Card Sorting: Discovering Possible Groupings
Card sorting is a research method in which study participants place individually labeled cards into groups according to criteria that make the most sense to them.
Card sorting is used to discover users’ mental models for how content should be grouped. Participants organize a set of cards representing pages, links, images, or page descriptions into groups that make the most sense to them.
Card sorting is typically conducted early in the design process to help designers generate ideas for possible navigation structures that align with users’ expectations.
Limitations of Card Sorting
Will researchers know the exact navigation structure after conducting a card sort? No.
At most, card sorting provides ideas for possible groupings. Often individual users will group the same content in different ways. Therefore, designers must use critical judgment and additional research to make final decisions about the navigation structure.
Tree Testing: Evaluating Navigation Structures
A tree test evaluates a hierarchical category structure, or tree, by having users find the locations in the tree where specific resources or features can be found.
Tree testing is used to validate a proposed or existing navigation structure by testing the findability of content. Users interact with a hierarchical menu that displays a series of accordions representing the categories of a site’s navigation.
Using a specialty type of unmoderated remote testing tool, like UserZoom or Treejack, participants find different types of content within the “tree” or information hierarchy. As the participant selects categories, the accordion expands to reveal subcategories, and users continue to click until they locate the subcategory, they believe contains the content they're tasked to find. Tree tests are usually conducted on an existing or proposed navigation structure. They play a crucial role in evaluating the findability of content on a site or application.
Limitations of Tree Testing
One thing to consider when running a tree test is that users only see an isolated hierarchy which isn’t a typical interaction when on a fully designed site. The tree-testing environment lacks context clues like placement, color, and images, which can sometimes provide information scent that helps users find content.
Card Sorting vs. Tree Testing
Purpose
Card sorting works best as a discovery method, uncovering user mental models and suggesting potential ways to organize content.
Tree testing is used to evaluate an existing or proposed navigation structure.
Employing both methods helps researchers determine a navigation design that is intuitive for users and aligns with their expectations.
Process
Card sorting requires participants to organize invidually labeled cards into groups according to criteria that make the most sense to them.
Tree testing requires participants to navigate a simplified text-based outline of the content structure.
As a result, card sorting presents ideas on how to organize content, while tree testing pinpoints areas of navigation structure that need clarity.
Tools
Both methods can be conducted in person, on paper, with either index cards (card sort) or paper prototypes (tree test).
However, researchers tend to prefer using online tools for both methods because they vastly expedite analysis. Optimal Sort is a popular tool for card sorting, while Treejack is commonly used for tree testing.
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Card Sorting vs. Tree Testing: What’s the Difference? |
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Card Sorting |
Tree Testing |
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Purpose |
To generate ideas for organizing content |
To evaluate an existing or proposed navigation structure |
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Process |
Participants organize cards into groups |
Participants navigate through an established hierarchy of content |
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Common Tool |
Optimal Sort |
Treejack |
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Type of Methodology |
Discovery |
Evaluative |
Conclusion
Card sorting and tree testing are complementary research methods that serve distinct purposes when designing an effective navigation and content structure. Knowing when to use each method helps you get the most out of your users and make optimal design choices. Both methods ultimately help researchers develop a navigation and content structure that aligns with user expectations and has strong findability.
