Originally Posted by InkUnderNails

Binary test results, such as go/no go gauges, are quite common in industry and serve a useful purpose. They alert the machine operator that an operation is out of tolerance. They do not say how much out of tolerance, or the cause of the intolerance, but they are accepted tools for process inspection.

The problem with binary test results and the TSA is that the failure of the test is cause for suspicion of the person, not cause for determination of the severity and source of the anomaly.

In industry, the failure of a binary process test puts in motion a range of qualifying tests to determine the severity of the problem, the source of the problem and the correction of the problem.

The TSA has no such tools at their disposal. Therefore, the result of the binary test is to assume the most severe causes and eliminate by inspection each of the possibilities. This would be considered a ridiculous methodology in industrial testing as the cost and time for resolution may be disproportionate to the severity of the problem.

Furthermore, applying the elimination by inspection process to humans just trying to get on a plane, becomes a humiliating and often a very uncomfortable process that almost universally ends up showing that no correctable problem exists. The TSA does not care. They have to resolve the binary alarm with the only tools at their disposal, inspection.

When your only tool is a hammer, every problem begins to look like a nail.