How does tree testing differ from card sorting, and what does it validate?

Card sorting is a generative method — it helps you build or refine an information architecture by learning how users mentally categorise content. Tree testing (also called reverse card sorting) is an evaluative method — it tests whether users can find items within an already-defined navigation hierarchy. Participants are given a text-only tree (no visual design) and asked to complete "find" tasks by navigating through it. Key metrics: success rate, directness (how many went straight to the answer without backtracking), and time-on-task. In Salesforce, tree testing validates whether users can locate a custom app, find a specific tab, or navigate a multi-level menu before investing in a full build. It isolates navigation problems from visual design problems, making it a clean test of information architecture alone.