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Chapter 16: C. Inspection Planning and Procedures 167
• The disposition of nonconforming units, for example, repair, scrap, or
salvage, and of rejected lots, for example, screen or return to vendor
• The criteria for initiating a review of the process, vendor, or inspector
2. INSPECTION ERRORS
Identify potential inspection errors such
as bias, fatigue, flinching, distraction, etc.
(Application)
Body of Knowledge III.C.2
Errors are bound to happen in any system that has a combination of interrelated
factors that make up an outcome. The inspection process itself involves many factors
that combine to determine the outcome of the inspection, often a decision.
Major contributors to error sources are:
1. Human error or errors due to the physiology of the inspector
2. Inspection equipment errors due to accuracy, instrument selection,
methodology, and so on
3. Errors due to the environment that surrounds the inspection location
4. Procedural errors due to the introduction of new processes, equipment,
and so on.
Inspection involves a measurement comparing the actual value of a measured
item, component, or material with a standard, and making a decision as a result of
such measurement. Measurement by itself has different error sources that are
often unavoidable.
Error in measurement is the difference between the indicated value and the
true value of a measured quantity. The true value of a quantity to be measured is
seldom known. Errors are classified as:
1. Random errors
2. Systematic errors
Random errors are accidental in nature. They fluctuate in a way that cannot be predicted
from the detailed employment of the measuring system or from knowledge
of its functioning. Sources of error such as hysteresis, ambient influences, or variations
in the workpiece are typical but not all-inclusive of the random category.
Systematic errors are those not usually detected by repetition of the measurement
operations. An error resulting from either faulty calibration of a local standard
or a defect in contact configuration of an internal measuring system is typical
but not all-inclusive of the systematic class of errors. It is important to know all
Part III.C.2