Summary: Users’ mental models of concept categories are far less strict than you might expect. Consider keeping small numbers of outlier pages within their larger parent category, rather than creating unnecessary subcategories.
If you’ve worked on building the information architecture for a website or app, you’ve probably encountered some items that were a bit tricky. It might be that they had several natural homes ( polyhierarchy ) or they fitted loosely into a single category. You’ve probably wondered how to handle this situation, asking yourself if you should create some specific subcategories for these odd items or just put them in the categories that they sort of belong to. You might have even thought about it in terms of how “strict” or “logical” your categorization needs to be.
Information architects often struggle with how similar things need to be in order to belong to the same category and, conversely, how different they should be in order to be split apart.
Card Sorts Reveal Unexpected Groupings
Card sorting is a commonly used research method for information-architecture projects. It involves asking users to group objects (cards) into piles that make sense to them. The idea is that if a large percentage of people assign an object to the same pile (or category), then the object can be safely put in that category in the final information architecture.