Humans may, depending on how they've been raised and what they've been told, miscjudge the likelihood of averse events. Many people think of nuclear power as dangerous when it really isn't. In many cases, this depends on the individual's available knowledge. Flying, for example, is exceedingly safe, and that fact is well known. But for those who do not know this, they may misjudge the risk.

This fact difference can be easily established by asking yourself “How likely is X to happen?” and then looking up how likely it really is. If your guess was spot on, you have a fear coefficient of 1. If your guess was twice as likely as reality, you have a fear coefficient of 2, and so on.

You can think of a coefficient differently though: When going into a dark attic or a dark basement, or even just at home late at night, we might sometimes get anxious. What if someone jumps out at us from the darkness? We know for a fact that the odds of that happening are virtually zero, but we can get afraid of that anyway. Even when we know that the likelihood of this is exceedingly low, we still feel fear as if it was quite likely to happen.

Humans are masters at making up threats where there are none, and humans are great at blending out threats that are really there. Cars, for example, are quite dangerous (especially in comparison to flight), but we routinely underestimate the risk of driving (though this may perhaps be a survival strategy to reduce stress in situations where no alternatives exist anyway).

In this case, the fear coefficient may be used to describe the actual likelihood of something happening in comparison to how much fear the person feels. If, for example, in the dark basement a person has so much fear that the person feels like there genuinely might be something, say, 50%, they have a very high coefficient. Their brain is preparing them for odds many orders of magnitudes higher than what is really there, so the fear coefficient may be around 100,000,000. In the same way, we get into cars with a confidence as if the odds of a crash approach zero, when in reality that isn't the case, we might have a fear coefficient of 0.2.

Perhaps more interesting than 2. is the comparison between individuals. In this metric, we compare a person's felt amount of fear to the average. Perhaps more statistically significant, we may also compare a person's guess on how likely something is in comparison to the average guess. If you think of something as twice as likely as what the average thinks, you have a fear coefficient of 2.

Another interesting way to measure fear is to consider how much risk a person is willing to take in certain situations. For example, car driving is a risk most of us take very frequently, and whatever odds of a crash we believe we do take is obviously not too much to stop us from driving cars regularly. The question is then about how much of a risk car driving would have to present to a person before they stop driving cars. These numbers can be used to derive a fear coefficient, either by comparing them to the real chance or by comparing them to the average or other individuals.

For example, if I boarded a plane on the condition that I'm okay with a 1:1000 chance of crashing, I would be comparatively bold because the real chance of a crash is ~1:12,000,000 roughly.

A big conversation about how fear is experienced between individuals was the Man or Bear? discussion.