INTRODUCTION TO SOFTWARE DESIGN FOR SIX SIGMA (DFSS) - Software Design for Six-Sigma: A Roadmap for Excellence - page 204

TABLE 8.A.1 Error-Proofing Methods

Method Explanation Example

Elimination Redesign product to avoid usage

of the component.

Redesign code to avoid use of
GOTO statements.

Replacement Substitute with a more reliable

process.

Replace multiple “If Then Else”
statements with a “Case”
statement.

Prevention Design the product such that it is

impossible to make a mistake.

Use polarized connectors on
electronic circuit boards.

Facilitation Combine steps to simplify the

design.

Reduce number of user
interfaces for data entry.

Detection Identify error before processing. Validate data type when

processing user data.

Mitigation Minimize effect of errors. Provide graceful exit and error

recovery in code.

From a software development cycle, this phase may be treated as an extension of
the Design phase.

8.A.6 DIDOVM PHASE: VERIFY

The Verify phase is akin to the Testing phase of a software development cycle.
Tools like Minitab are used extensively in this phase where statistical tests and Z
scores are computed and control charts are used extensively to determine how well
the CTQ(s) are met. When performing response time or other performance related
tests, it is important that the measurement system is calibrated and that errors in the
measurement system are avoided. One technique used to avoid measurement system
errors is to use instruments from the same manufacturer so that testers can avoid
device-related errors from creeping in.
The example in Figure 8.A.10 relates to the DVD player example where the
“content feedback time” CTQ performance was verified. Notice that the score for
Z is very high, indicating that the extent of variation in the measured metric is
very low.
One aspect to be kept in mind when it comes to software verification is the aspect
of repeatability. Because software results often are repeatable, the Z scores often
tend to be high but the results can be skewed when tests are run in conjunction with
the hardware and the environment in which the system will operate in an integrated
fashion.

8.A.7 DIDOVM PHASE: MONITOR

It is in this phase that the product becomes a reality and hence the customer response
becomes all the more important. A high spate of service calls after a new product