SOFTWARE QUALITY CONCEPTS - Software Design for Six-Sigma: A Roadmap for Excellence - page 13

DISCOVERED
DURING PROCESS

DISCOVERED
INTERNALLY
(AFTER PROCESS
COMPLETION)

DISCOVERED
BY CUSTOMER

100X

10X

1X

FIGURE 1.2 Internal versus external quality cost rules of thumb.

that the PR group has to spend to cope specifically with potentially bad publicity
because of bugs is a failure cost. COPQ is the sum of appraisal, internal and external
quality costs (Kaner, 1996).
Other intangible quality cost elements usually are overlooked in literature (see
Figure 1.3). For example, lost customer satisfaction and, therefore, loyalty, lost sales,
longer cycle time, and so on. These type of costs can alleviate the total COPQ, which
handsomely can be avoided via a thorough top-down DFSS deployment approach.
See DFSS deployment chapters for further details (Chapter 8).

1.7 SOFTWARE QUALITY MEASUREMENT

The software market is growing continuously, and users often are dissatisfied with
software quality. Satisfaction by users is one of the outcomes of software quality and
quality of management.

Maintenance and
service

Usually
Measured

Retrofits

Wa rra nty c l ai m s

Rejects

Rework

Service recalls

Downtime

Additional labor
hours

Scarp Scrap

Opportunity cost if sales
greater than capacity

Cost to customer

Expediting

Redesign

Brand reputation

Improvement program costs

Excess inventory

Lost customer loyalty

Quality engineering and
administration

Process control

Lost sales

Not
Usually
Measured

Poor product availability

Vendor control

Quality audits

Longer cycle times

Inspection/test (materials,
equipment, labor)

FIGURE 1.3 Measured and not measured quality cost elements.