Other uses of simulation
Simulations can help us to answer questions about a variety of other models (or populations). The following example shows another simple simulation.
Is security at LA International Airport as good as elsewhere?
In 1987, the Federal Aviation Administration (FAA) investigated security at Los Angeles International Airport (LAX). In one test, it was found that only 72 out of 100 mock weapons that FAA inspectors tried to carry onto planes were detected by security guards (Gainesville Sun, Dec 11, 1987).
Is the FAA justified in claiming that this "detection rate was well below the national rate of 0.80"?
A simulation
If the detection rate at LAX was the same as elsewhere, and every weapon independently has probability 0.80 of being detected, we know that the number detected out of 100 weapons will be a random quantity.
How unlikely is it to get as few as 72 out of 100 weapons detected if the probability of detection at LAX is 0.80 — the same as elsewhere?
A simulation helps to answer this question.
Click Simulate to randomly 'try to get 100 weapons onto planes', with each independently having probability 0.80 of detection. Click Accumulate then run the simulation between 100 and 200 times. (Hold down the Simulate button to speed up the process.)
Observe the distribution of the number of weapons detected. The proportion of simulations with 72 or fewer weapons being detected is shown to the right of the dot plot. Observe that this rarely happens.
We therefore conclude that the FAA's claim that LAX has a poorer detection rate than elsewhere is justified — only 72 weapons being detected would be unlikely if the detection rate was really 0.80.
We will return to this example later.