Definition:Claim severity
📊 Claim severity refers to the average monetary cost of individual claims within a given portfolio, line of business, or time period. Unlike claim frequency, which counts how often losses occur, severity measures how expensive each loss turns out to be. Insurers, reinsurers, and actuaries track severity closely because even a stable frequency trend can mask a deteriorating book if the cost per claim is climbing — a pattern common in lines such as commercial auto, medical malpractice, and workers' compensation.
⚙️ Severity is typically calculated by dividing total incurred losses by the number of closed or reported claims over the same period. Analysts often segment the metric by line of business, geography, or policy year to spot emerging trends. In excess-of-loss reinsurance arrangements, severity is the dominant risk factor: a treaty attaching at $500,000 is primarily exposed to the tail of the severity distribution rather than the volume of claims underneath that threshold. Catastrophe models also rely on severity assumptions to estimate per-event losses from natural disasters, feeding directly into probable maximum loss calculations.
💡 Understanding severity dynamics is essential for accurate loss reserving and rate making. When severity trends outpace the rate adequacy assumptions baked into pricing, an insurer's loss ratio deteriorates — sometimes long before the problem surfaces in financial statements, because claims can take years to develop fully. Monitoring severity also helps claims teams allocate resources: high-severity lines may justify dedicated specialist adjusters, litigation management programs, or subrogation efforts that would not be cost-effective on lower-severity portfolios.
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