The in the Sigma Six cost-of-quality (COQ) equation includes the internal costs before the product is sold (like waste and re-work).

Cost of Failure

Explanation:

A manufacturer incurs failure cost when they produce defective goods. The can be both internal and external cost.

Internal cost are those that incur before the product is sold/shipped to the ultimate buyer such as waste, re-work and/or reduction in sales price for re-worked goods. External cost on the other hand are those that occur following the shipment of goods such as warranty claims, cost of any legal action taken by customer, orders cancelled and/or lost of customer goodwill.

In most cases the external cost is higher than the cost incurred on the internal failure of the goods. So most often the manufacturers are more focused on ensuring that the quality standards are achieved.