What determines the weight of a risk?
The weight of a risk can be described as the severity of the possible harm that might occur from a given activity multiplied by the probability of the harm occurring. This can be expressed by the following equation:
(weight of risk) = (severity of harm) x (probability of occurrence)
Generally speaking, higher risk activities have higher probabilities of more severe harm, while lower risk activities have lower probabilities of less severe harm. For example, russian roulette would be considered a very high risk activity (perhaps a 1 in 5 chance of death) while reading a book would be considered a very low risk activity (perhaps a 1 in a million chance of a paper cut). Of course, harm that one person considers extremely severe another person might not care about very much at all. Like benefits, “harms” are also largely subjective, and different people can assess their severity differently.