Professional assessment of insurance risk
An Actuary is a person employed by the insurance industry to calculate the level of risk an applicant for an insurance policy presents. This isn't done on an individual basis, but on a demographic basis.
Various factors will be combined to provide a calculation of risk for someone or a situation which meets certain set criteria, and this calculation will be used to set the level of premiums to be paid.
For example, a young driver will automatically fall into a higher risk demographic than a more experienced one, and this is down to the rules that actuaries formulate.
Likewise, more powerful cars will attract higher insurance premiums than smaller ones. This is not only because bigger cars are usually more expensive and therefore more costly to repair or replace, it's also because the trend is that the more powerful the car, the more aggressively it will be driven, and it is also more likely to be driven by a male than a female.
Thousands of similar trends and rules are used depending on the policy type, with the aim of predicting how much a policy is likely to cost an insurer on average, and price it accordingly.