Biomedical Engineering Reference
In-Depth Information
repetition, and human factor problems like task diffi culty.
Once again, it is critical to document everything in the
challenge.
This challenge provides a greater degree of assurance
about the resulting evidence because it is an objective test of
the procedure's applicability. However, it does not control a
number of internal and external threats to validity. Internal
threats to validity, such as history effects or maturation
effects, may provide plausible alternative explanations of the
resulting evidence.
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The revised procedure may “look” better than the current
procedure, but it may appear so because this particular
operator, at this time and place, performs better because she
or he got the prized place in the company parking lot that
morning. External threats to validity (and the associated
threats to “transferability”), such as expectancy effects, also
called Rosenthal effects, may limit the generalizability of the
resulting evidence. The operator may perform better because
the vice-president of technical operations has inadvertently
communicated her expectations for the real-world challenge.
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Nonetheless, it provides more credible fi ndings for the
decision either to proceed with versioning up the SOP, or to
introduce further revisions in the procedure.
Suppose that management cannot make a decision about
the applicable standard, say the concentration of the
sanitizing solution, by means of management review, peer
review, or the real-world challenge. Conducting a
study
based on an experimental design
is an option that management
can consider. Such a study will control for internal and
external threats to validity, thereby providing credible
fi ndings for the requisite decision.
The proposed study is a randomized design examining the
effi cacy of several levels of concentration of the solution as
applied to randomly selected sites in the facility.
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