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By Kris Ringwall; Beef Specialist North
Dakota State University
From Beef Talk -- July 16, 2004
Excerpt -- for complete article, please
visit North
Dakota State Univeristy.
This article provides a clear explanation
of the "inconclusive" test results for BSE
recently released by USDA. The author compares the false
positive tests to fire drills, a more common form of
false positives to which we can all relate. Clearly
it is okay to have false positives while it is totally
unacceptable to have false negatives.
"People have gradually shifted their
thinking toward the concept of absolutes rather than
variations within the world. This may not be a major
discussion point, but certainly the recent events involving
the inconclusive tests for BSE (mad cow disease) remind
us that modern technology works. The process may or
may not be as simple as everyone would like, but the
process works.
A test where the results indicate a positive
reading, but in reality the sample is really negative,
is not a new phenomenon. False positive test results
have been around for a long time.
As testing processes have been developed
through the years, two potential errors have always
existed, the false positive and the false negative.
For a test to have the highest level of accuracy, any
occurrence of false negatives, i.e. a sample that is
really positive but is not picked up by the test, is
totally unacceptable.
False positive results have not been as
detrimental as false negatives, and have been allowed
to exist, along with subsequent development of additional
tests, to help further reduce the incidence of a false
positive. The false positive is the process of calling
or labeling a sample as positive when in reality the
sample is negative.
Can the industry live with false positives?
The answer is yes, but the consumer or affected party
needs to better understand what test results really
mean. In the case of the false positive test for BSE,
there was no danger to the food supply and the general
public remained safe.
A fire drill is a good analogy to explain
a false positive test. Most people should be well versed
in the functioning of a fire drill. From the first day
of grade school, people are taught what a fire alarm
is and what to do when one sounds.
Upon hearing the sound of the alarm, everyone
must leave the building or premises. The logic is that
the sooner all people leave the premises, the less likely
anyone will be hurt in the event of a fire. The principle
works and has saved many lives."
Full
Story...
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