Research methods
Closed card sort
A card sort where participants place items into categories you have already defined. It tests whether a proposed structure makes sense.
In a closed sort the groups are fixed and participants only decide where each card goes. The results show which items fit cleanly and which ones people disagree about.
It is useful once you have a draft structure. Adding a 'Not sure' group stops people being forced into a guess, and the cards that land there are often the most informative.