A way of analyzing receivable balances is to use the Gentry-De La Garza model . Thismodeldescribes three reasons why accounts receivable balances may increase: sales pattern effects, collection experience effects, and joint effect. Sales pattern effects are increases in receivables due solely to increases in sales. The increase in accounts receivable is partly a function of increasing sales (the sales pattern effect), partly a function of the deterioration in collections (the collection experience effect), and some combination of both (the joint effect). The joint effect is explained as the increase in receivables due to a simultaneous deterioration in collections and increase in sales. For instance, some customers may have purchased the product with the assumption that they could pay late; this would both increase sales and slow collection. The joint effect is calculated by taking the difference between the current and past collection experience effects and then multiplying this difference by the difference between the current and past sales levels. Finally, the sales pattern effect is quantified by taking the difference between the current and past sales levels multiplied by the prior collection experience effect. The sum of the sales pattern effect, joint effect, and collection experience effect equals the difference between the receivables balances. The advantage of the Gentry-De La Garza model is that it separates the increase in receivables into three quantifiable components. A financial manager then can see clearly if an increase in receivables results from faulty credit controls or if the increase is simply consistent with rising sales levels. Deteriorating collections might indicate that credit is granted too freely or that the company is not persistent enough in collecting overdue accounts. Both problems fall under the control of the credit department and are the primary responsibility of the credit manager.