An area of the store can support sales, exposure, or assistance. Its usefulness depends on the assigned function and the alternatives of use. Comparing only turnover per area can penalize spaces that facilitate purchases made elsewhere or make the service viable.
I propose to describe what is happening in the area and what results it should sustain. For an exhibition, the possibility of recognizing products counts; for a service point, the quality of the conversation counts. The same measure does not represent different functions well.
Let's imagine a space dedicated to trying a product. Sales can be recorded at checkout, while the usefulness of trying the product remains invisible. Observing requests, use and related purchases helps interpret the contribution, while keeping the attribution of the results prudent.
A limited change may allow comparison, as long as they consider turnout and availability of products. The final choice concerns the organization of the entire store. Space gains value when it advocates customer-friendly behavior that is compatible with the resources of the business.