Just by walking through their doors you're f***ing their metrics. All major retailers worth their salt track customers coming and going and then calculate return on visit (return as in $) and conversion (turning a visiting customer into a sale).
By walking in the door and not buying anything you're lowering the ROV and conversion, if you buy something you increase conversion and alter ROV which is the average sale for the time period.
At staples our tracking system was so complicated it could effectively staff a store, it told us how many people to expect on a day, at what times, what products would be more in demand at said times (toner in the lunch rush, home ink after 5 for instance) and well, just about everything. The system mixed with our store planning as well so you could digitally map traffic patterns and use that information for advertising space.
But the take away here is simple- you can f*** with metrics just by walking in the door.
That must be confusing for stores that also serve as a mall entrance.
I passed by Dicks yesterday to get an expensive piece of gym equipment and continued past them over to Gym Source.