Detection of concealed weapons at LAX

Use this example to explain that we are more interested in the population proportion of weapons detected— the proportion that would be detected if an infinitely large number of weapons were attempted — than the proportion detected in this specific sample.

This population proportion is unknown but the sample proportion, p = 0.72, throws some light on it.

A series of tests of airline and airport security was conducted by the Federal Aviation Administration (FAA). The Gainesville Sun on 11 December, 1987 reported the results from one series of tests, in which FAA inspectors tried to carry mock weapons on board planes at Los Angeles International Airport (LAX) 100 times. Only 72 of these were detected by security guards.