When calculating the business situation for a Six Sigma job, the cost of bad top quality (COPQ), which is the price led to via producing defects, is a typically offered idea. Within the total amount of top quality expense, yet, COPQ represents only a particular proportion. Costs carry out not outcome from just producing and solving failures; a high amount of expenses comes from ensuring that excellent products are developed. This write-up describes the price of high quality as a much more comprehensive concept extending the cost of negative high quality and the expense of excellent high quality. In short, any cost that would not have actually been expfinished if high quality were perfect contributes to the expense of high quality.

Cost of Quality

As characterized by Philip B. Crosby in his book Quality Is Free, the expense of quality has actually two major components: the cost of good top quality (or the price of conformance) and also the expense of bad top quality (or the expense of non-conformance). As Figure 1 shows:

The cost of bad high quality affects:Internal and external costs resulting from failing to satisfy requirements.The expense of excellent high quality affects:Costs for investing in the avoidance of non-conformance to needs.Costs for appelevating a product or service for conformance to demands.

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Figure 1: Cost of Quality

Cost of Poor Quality: Internal Faitempt Costs

Internal failure expenses are prices that are brought about by commodities or services not conforming to demands or customer/user demands and are discovered prior to shipment of commodities and also solutions to outside customers. They would have otherwise led to the customer not being satisfied. Deficiencies are brought about both by errors in assets and inefficiencies in procedures. Examples encompass the prices for: 

ReworkDelaysRe-designingShortagesFaitempt analysisRe-testingDowngradingDowntimeLack of adaptability and also adaptability
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Cost of Poor Quality: External Faiattract Costs

External faiattract costs are expenses that are resulted in by deficiencies discovered after delivery of products and also services to exterior customers, which result in customer dissatisfactivity. Examples encompass the prices for: 

ComplaintsRepairing goods and also redoing servicesWarrantiesCustomers’ poor willLosses because of sales reductionsEnvironmental costs

Cost of Good Quality: Prevention Costs

Prevention prices are costs of all activities that are designed to prevent poor high quality from emerging in assets or services. Examples include the prices for: 

Quality planningSupplier evaluationNew product reviewError proofingCapcapability evaluationsQuality advancement team meetingsQuality innovation projectsQuality education and also training

Cost of Good Quality: Appraisal Costs

Appraisal costs are costs that occur bereason of the must manage assets and services to ensure a high high quality level in all stperiods, conformance to quality requirements and performance demands. Examples encompass the expenses for: 

Checking and also trial and error purchased items and servicesIn-process and last inspection/testField testingProduct, process or service auditsCalibration of measuring and test equipment

The total top quality expenses are then the amount of these costs. They recurrent the difference between the actual expense of a product or service and the potential (reduced) price provided no subtypical service or no defective products. 

Many kind of of the expenses of high quality are hidden and also difficult to determine by formal measurement systems. The iceberg version is incredibly regularly used to highlight this matter: Only a minority of the expenses of poor and good high quality are obvious – show up above the surface of the water. But tbelow is a huge potential for reducing expenses under the water. Identifying and also enhancing these costs will substantially minimize the expenses of doing organization. 


Figure 2: The Iceberg Model of Cost of Quality

The Six Sigma Philosophy of Cost of Quality

What is the relation in between the price of excellent top quality and also the price of poor quality? The conventional watch would be to conclude that if a company desires to alleviate defects and also by this alleviate the expense of bad top quality, the price of great quality would have to be enhanced, definition higher investments in any type of kind of checking, experimentation, review, training of operators, and so on. Following the Six Sigma philosophy, however, of structure high quality right into procedure, service and also assets and also doing things best the initially time, the increase of the price of excellent quality, while striving for zero defect performance, can be smoothed if processes get better. 

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As Figure 3 mirrors, company processes through better procedure sigma will have substantially lower prevention and also appraisal costs. Although you will certainly never fully get rid of appraisal and prevention prices (as opposed to failure expenses that in an ideal zero defect human being would certainly also be zero), their reduction as a result of much better process performance will be considerable. 

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Figure 3: Classic Management View vs. Six Sigma Philosophy

Table 1 reflects how dramatically the expense of high quality as a percent of sales decreases if the process sigma enhances. 

Table 1: Sigma Level and the Cost of Quality

Sigma Level


Cost of Quality as Percentage of Sales



More than 40%












Less than 1%

Assuming that the average performance of a firm is 3 sigma, 25 percent to 40 percent of its yearly revenue gets chewed up by the cost of quality. Hence, if this firm can enhance its quality by 1 sigma level, its net earnings will certainly boost hugely.