At the most basic level, initial ratemaking involves looking at the frequency and severity of insured perils and the expected average payout resulting from these perils. Thereafter an insurance company will collect historical loss data, bring the loss data to present value, and compare these prior losses to the premium collected in order to assess rate adequacy.[24] Loss ratios and expense loads are also used. Rating for different risk characteristics involves at the most basic level comparing the losses with "loss relativities"—a policy with twice as many losses would therefore be charged twice as much. More complex multivariate analyses are sometimes used when multiple characteristics are involved and a univariate analysis could produce confounded results. Other statistical methods may be used in assessing the probability of future losses.
At the same time, the first insurance schemes for the underwriting of business ventures became available. By the end of the seventeenth century, London's growing importance as a center for trade was increasing demand for marine insurance. In the late 1680s, Edward Lloyd opened a coffee house, which became the meeting place for parties in the shipping industry wishing to insure cargoes and ships, and those willing to underwrite such ventures. These informal beginnings led to the establishment of the insurance market Lloyd's of London and several related shipping and insurance businesses.[6]
To "indemnify" means to make whole again, or to be reinstated to the position that one was in, to the extent possible, prior to the happening of a specified event or peril. Accordingly, life insurance is generally not considered to be indemnity insurance, but rather "contingent" insurance (i.e., a claim arises on the occurrence of a specified event). There are generally three types of insurance contracts that seek to indemnify an insured:

Retrospectively rated insurance is a method of establishing a premium on large commercial accounts. The final premium is based on the insured's actual loss experience during the policy term, sometimes subject to a minimum and maximum premium, with the final premium determined by a formula. Under this plan, the current year's premium is based partially (or wholly) on the current year's losses, although the premium adjustments may take months or years beyond the current year's expiration date. The rating formula is guaranteed in the insurance contract. Formula: retrospective premium = converted loss + basic premium × tax multiplier. Numerous variations of this formula have been developed and are in use.
One of the best ways to get cheap car insurance is by comparing car insurance quotes — and the companies offering them. To get you started, NerdWallet looked at car insurance prices across the country for different driver profiles and coverage levels to find the cheapest rates. We’ve sliced the data in several ways to give you an idea of average costs and what factors might nudge your car insurance rate up — or even better, down.