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2.
Quality Control
 
Quality control
refers to the specific ways of implementing various points of the
quality assurance program. This includes all aspects of day-to-day laboratory
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Good Laboratory Practice — Establishing Validity and Reliability
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operation such as instrument maintenance, reagent preparation, and the
proper use of standards and controls. The latter is the only aspect that we
will address in detail at this point.
 
a.
Standards and Controls
For the science in forensic science to be taken seriously, each analytical test
must be accompanied by the appropriate standards and controls. These will
differ depending on the kind of analysis, but their conspicuous absence is
unacceptable. Again, for strictly comparison evidence, there is usually no
system to test, so standards and controls, in the sense that we discuss them
here, are not relevant.*
More than a few analysts include standards and controls in their exam-
inations only to meet some new-fangled post-modern standard, but fail to
truly understand their utility and necessity. No academician would be caught
dead publishing the results of an experiment without including both verifi-
cation that the test system was working as expected (positive controls) and
confirmation that no extraneous material had been introduced into the sys-
tem that would skew the results (negative controls). Because we have relin-
quished full control over the conditions in a forensic test by acknowledging
the limits of the sample, it is even more crucial that we confirm that the test
system is functioning as expected.
We should probably start by defining the terms 
 
standard
and 
 
control
.
These terms are typically used rather loosely and interchangeably. While it’s
true that their functions can overlap, and sometimes the same sample can
fulfill both requirements, it will be useful for the purposes of this discussion
to give you our working definitions.