| i | = | 1,…, 214 pharmacies providing usable responses |
| Ai | = | costs allocated to prescription department on square-footage basis |
| Bi | = | costs allocated to prescription department on percent of sales |
| Ci | = | costs solely in prescription department |
| Di | = | total prescription department labor costs |
| Ii | = | inflation adjustment where required |
| Rxi | = | total prescription volume for ith pharmacy |