逆向选择条件下带奖惩金的两期保险契约模型及其Pareto改进性研究

为了更有效的规避影响保险市场交易效率的逆向选择问题,本文分投保人风险类型为两种和多种情形建立了带奖惩金的两期保险契约模型,首次提出可以用奖励金和惩罚金有效甄别投保人的风险类型。该模型根据投保人第一个保险期内的索赔情况在第二个保险期对其进行奖励或惩罚,高风险类型的投保人如果选择为低风险类型投保人设计的保险契约,则其在第二阶段受到惩罚的概率要远远大于得到奖励的概率,即风险越高的投保人越害怕惩罚金,因此所建模型满足斯彭斯-莫里斯分离条件。带奖惩金的两期保险契约模型中保险公司的期望利润仍然为0,并不会给投保人带来额外的经济负担,却能够实现对传统部分保险契约简单重复两次的严格帕累托改进。最后采用一个算例说明了该模型的有效性。

Research of Two-stage Insurance Contract Model with Bounties and Penalties and Pareto Improvement Under Adverse Selection

In the markets of insurance, there extensively exists information asymmetry which causes the phenomenon of adverse selection, in order to avoid this phenomenon more effectively that influences the efficiency of insurance market, the two-stage insurance contract models with bounties and penalties were established according to the two and multiple risk types of insureds in this paper, which shows that bounties and penalties can be used to distinguish the risk types of policyholders for the first time. These models indicate that in the second period of insurance the insurers can give the insured bounties or penalties in terms of the claim or not by policyholders in the first period, the probability of obtaining penalties is far more greater than bounties in the second period if the insureds of high-risk choose the insurance contract designed for the low-risk, namely the high-risk policyholders are more afraid of penalties and thus the model meets Spence-Morris separation condition. This insurance contract model with expected profits of insurers still being zero, which does not lead to extra economic burden for insureds, can yet realize the strict Pareto improvement compare to the two-time repeat model of traditional partial insurance contract. Furthermore, the insurance contract model with bounties and penalties proves that as long as the insureds with each different risk type are incentive compatible to the policyholders of the highest risk type, they are incentive compatible to every risk type of insureds, which greatly simplifies the two-period insurance contract model under the conditions of various risk types. An example is given to illustrate the effectiveness of the model at last. In addition, our study not only presents a new screening tool, but also make a major step forward in the research of Multi-period dynamic insurance contract.