医疗保险讲义课件

❖ 约翰的财富的效用 John’s utility of wealth
如果他购买保险，其确定效用＝
if he would buy insurance, his certainty utility=
U(财富=19500)=178 如果他不愿购买保险，其期望效用＝
if he wouldn't buy insurance,his expected utility=
他也可以自我保险 He can self-insure ❖ 生病概率小，但是一旦生病损失很大 small possibility of a large loss if the illness occurs ❖ 不生病的概率大，也没有医疗支出 large possibility that the medical loss will not occur
保险费＝预期医疗保健支出
insurance premium= expected health care expenditure
=95%× 0 + 5%×10,000
=500
他的财富＝ 20,000-500=19500
His wealth =20,000-500=19500
他的确定效用＝
His certainty utility=
医疗保险 Health Insurance
❖ 医疗保险 Health surance
提供一种分散由疾病引起的财务风险的方式
Provide a way to diversify financial risks associated with illness
❖ 医疗保险的需求理论
The theory of demand for health insurance
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医疗保险 Health Insurance
❖ 两种可选的行动方案 Two alternative courses of action
他可以购买保险，承担一个数目不大的保险费 He can
purchase insurance and incur a small loss in the form of the insurance premium
John has $20,000 annual income, no saving and borrowing
健康的概率95% ，医疗支出为0，财富为$20,000 With
95% probability, he will be healthy. When he is healthy, his health care expenditure is 0 and his wealth is $20,000
He will be better off if he buys insurance
不确定性导致效用损失
uncertainty leads to a loss of utility
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医疗保险 Health Insurance
❖ 效用函数对购买保险行为的影响
个人希望最大化其效用
An individual wishes to maximize his or her utility
如果事件确定，每个人最大化其确定的效用
if there are certain events, individual maximizes his or her certainty utility
=probability of illness × utility of wealth with illness + probability of healthy × utility of wealth with healthy
❖ 例子，假设 Example, assume
约翰有$20,000 的年收入，年内没有储蓄和贷款
问题：哪种选择可以使他的效用最大化？
Question: which choice provides him with a higher level of utility
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医疗保险 Health Insurance
❖ 如果约翰购买医疗保险 If John would buy health insurance
生病的概率5% ，医疗支出$10,000 ，财富$10,000
with 5% probability, he will be sick. When he is sick, his
health care expenditure is $10,000 and his wealth is
reduced to $10,000.
5% ×U(w=10,000) + 95% × U(w=20,000) =5% × 100 + 95% × 180 = 176
❖ 约翰的确定效用大于期望效用
John’s certainty utility is greater than the expected utility
如果购买保险，情况将得到改善
❖ 约翰的偏好——财富的效用
John’s preference--utility of wealth
财富 效用 边际效用
❖
10,000
100
❖
12,000
130
❖
14,000
155
❖
16,000
168
❖
18,000
176
❖
19,500
178
❖
20,000
180
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医疗保险 Health Insurance
❖ 如果约翰不愿购买医保 If John wouldn't buy health insurance
他的财富将是$20,000 或者$10,000
his wealth could be $20,000 or $10,000
他的预期效用＝
his expected utility=
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医疗保险 Health Insurance
如果事件不确定，每个人最大化其期望效用
if there are uncertain events, individual maximizes his or her expected utility
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医疗保险 Health Insurance
❖ 期望效用 Expected utility
＝生病的概率×生病时的财富所带来的效用＋健康的概率× 健康时的财富所带来的效用