Property insurance frequently contains a "coinsurance clause" stating that, if the insured values its property at some fraction

of its actual value

, and

is less than a coinsurance percentage

(often 80%), the insurer may reduce its payment to

of the loss. By way of example, if a house were insured for $140,000, which was a fraction 0.7 of its actual value of $200,000, and the coinsurance percentage were 0.8, the insurer would have to pay only $70,000 following an insured $80,000 loss to the insured. This provision is intended to deter deliberate underinsurance of property, which can work to the insurer's disadvantage when premiums are a linear function of the value the insured places on the property.

This Demonstration permits exploration of work done by Professor Itzhak Venezia involving whether a knowledgeable insured would prefer such a coinsurance provision to an alternative payment structure. More specifically, it compares an insurance policy with valuation fraction α and coinsurance percentage

to an alternative insurance policy that had no coinsurance requirement but whose valuation percentage β was lower than α. In the "basic controls" bank, the user sets

,

, and

with sliders. In the "advanced controls" bank, the user determines whether statistics on the distribution of wealth will be computed. Doing so will significantly reduce the responsiveness of the other controls. The user selects alternative parameters to the transformed beta distribution of wealth. The user selects the initial wealth of the insured, the actual value of the nsured property and whether any multiplicative load is placed on the premium for purposes of computing the statistics of the wealth distribution.

*Mathematica* outputs graphs showing insurance payments and wealth as a function of loss and a graph showing the cumulative distribution of wealth under both insurance policies. It further output a table showing the value of α that equilibrates premiums under the two insurance policies and, if "advanced computations" is checked, statistics on the distribution of wealth that results when this equilibrating value of α is used. The statistics confirm that for the same money, the insured has lower risk when using a policy with a coinsurance requirement.