Number of claims relative to exposure, the first driver of pure premium alongside severity.
Frequency is the ratio of claim count to the corresponding exposure (policy-years, vehicle-years, sums insured). Together with severity it decomposes risk into two independent drivers, the basis of a priori pricing: pure premium = frequency × severity. A frequency of 0.12 means 12 claims per 100 policy-years of exposure. Exposure must be consistent with the claim count definition. Frequency is sensitive to the claim definition used (with or without deductible), seasonal effects and behavioral changes. Longitudinal monitoring detects loss trends before severity reveals their magnitude.
Motor book: 1,200 claims / 10,000 policy-years = 0.12 frequency (12%). Multiplied by 3,000 EUR severity, pure premium = 360 EUR.
claim frequency, taux de fréquence, frequency, fréquence sinistres