I would look at the following:
1) Average check
- Length of the check
- Product mix in the check
Key check drivers:store format (space and assortment / price / product quality), promo & discounts, personal sales (fashion, electronics), loyalty programs, merchandising, stock availability, etc.
2) Number of customers
- Conversion - important in fashion and consumer electronics. less relevant for grocery
Key customer drivers: Location, Time opened, brand awareness, store format (space and assortment / price / product quality), external factors (parking, signage, etc), in-store experience (queues, look and feel, etc)