Page 231 - The Six Sigma Project Planner

True Value Method of Evaluation Comments
Inspector Concurrence • Metrics:
Study: 1. Inspector repeatability
A set of carefully identified 2. Inspector reproducibility
objects is chosen to represent 3. Stability
the full range of attributes, to
the extent possible. 4. Inspector “linearity”
1. Each item is evaluated by • Like a round robin, except true value isn’t
every inspector at least known.
twice. • No measures of accuracy or bias are
possible. Can only measure agreement
Unknown between equally qualified people.
• Full range of attributes included.
• People know they’re being watched, may
affect performance.
• Not routine conditions.

• Special care must be taken to ensure rigor.
TEAMFLY
• Acceptable level of performance must be
decided upon for each type of error.
Consider cost, impact on customers, etc.

Example of Attribute Inspection Error Analysis
Two sheets with identical lithographed patterns are to be inspected under carefully
controlled conditions by each of the three inspectors. Each sheet has been carefully
examined multiple times by journeyman lithographers and they have determined that
one of the sheets should be classified as acceptable and the other as unacceptable. The
inspectors sit on a stool at a large table where the sheet will be mounted for inspection.
The inspector can adjust the height of the stool and the angle of the table. A lighted
magnifying glass is mounted to the table with an adjustable arm that lets the inspector
move it to any part of the sheet. (See Figure 39.)

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Team-Fly
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