Definition
Actuarial science is the application of probability and statistics to the financial management of risk. Actuaries price insurance premiums, set reserves for future claims, design pension schemes, and assess solvency — all by modelling uncertain future events with probability distributions and discounting expected cash flows.
The profession dates to the 17th-century work on life annuities by John Graunt and Edmond Halley; modern actuaries use the full toolkit of probability theory, statistics, and financial mathematics.
Why it matters
How it works
An actuary models the underlying probability distribution of losses (claim sizes, frequencies, mortalities) using historical data, then computes expected values, variances, and tail percentiles. Premiums are set so the expected premium income covers expected claims plus expenses and risk margins. Reserves are established at conservative percentiles of the loss distribution.
Pensions add an additional layer: long-horizon mortality, interest-rate, and inflation forecasts must be combined with stochastic models to estimate the cost of guaranteed retirement income. The whole field is applied probability with financial consequences measured in billions.