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Post by ck4829 on Dec 15, 2016 11:00:55 GMT -6
PORTLAND, Ore. — Police agencies nationwide have for decades relied on field tests to screen for suspected drugs. Most test kits include small vials inside a plastic pouch. Officers put suspected drugs into the pouch, seal it, break the vials, then check to see if the fluid inside the pouch turns a certain color that indicates the presence of an illegal drug like cocaine. But who tests those tests? Do the test kits just react to the drugs listed on the test package, or can something else trigger positive results? Critics like John Kelly say they can and do. “These tests have been the source of many, many wrongful convictions,” says Kelly, author of a 2008 publication called “False Positives Equals False Justice,” which questions the validity of those field drug tests. “We were testing these tests and that happened with one of our tests. We just, we just put it for a second on the windowsill and in this case I think it turned positive for marijuana." katu.com/news/local/multnomah-county-reviews-field-drug-test-guilty-pleas-asks-that-some-be-dismissedRead more: burnoatus.freeforums.net/thread/341/drug-false-positives-multnomah-county#ixzz4SvXCsEBR
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Post by Logan on Dec 16, 2016 6:13:03 GMT -6
From a statistical standpoint I believe that what you are describing is known as a beta false positive. The firms that sell the test kits know that their market is are more concerned about having a low alpha false negative rather than a high false positive.
In other words, there is more money to be made not only in selling the tests but by law enforcement and the judicial system if more people are arrested and convicted. Who cares if some innocent person gets caught in the trap--they don't have the money to dispute the results of the tests.
The only acceptable testing for any chemical compound would involve spectroscopic testing such as gas chromatography, infrared spectrometry, mass spec or nmr. However, the cost of purchasing and maintaining the equipment along with the trained technicians and chemists to interpret the results is far too expensive--particularly if more tests turn out negative than the cheap field test packets.
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