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Timedbean · 2024年10月16日

另外一种算法

NO.PZ2023091802000188

问题如下:

An actuary at an insurance company is validating a newly implemented model that calculates the expected future payoff of term life insurance policies. The actuary spot checks the model’s calculations by using an example of a 70-year-old policyholder with a term life insurance policy. The policy pays out USD 350,000 if the policyholder dies at the age of 72 before turning 73, and pays nothing otherwise. The actuary uses the following information to calculate the expected future payoff of this policy:


Assuming any payout occurs at the end of the year, what is the closest value to the expected payout on this policy?

选项:

A.

USD 5,358

B.

USD 5,367

C.

USD 6,389

D.

USD 6,477

解释:

C is correct.

Payoff = amount of insurance payment * probability that the person will live until 72 and die at the age of 72 = 350,000 * (cumulative survival probability at 72/ cumulative survival probability at 70 * probability of death within 1 year at 72) = 350,000 * 0.79911/0.82573 * 0.018861 = 6,389

A is incorrect. Probability of dying at 72 is calculated as: cumulative survival probability at 70 * (1 probability of death within 1 year at 71) * probability of death within 1 year at 72

B is incorrect. Probability of dying at 72 is calculated as: cumulative survival probability at 71 * probability of death within 1 year at 72

D is incorrect. Probability of dying at 72 is calculated as: cumulative survival probability at 73 / cumulative survival probability at 72 * probability of death within 1 year at 72

请问可以用下面的方法计算吗,我算出来也是一样的答案。我怕是瞎猫碰上了小老鼠

(1 - 70岁一年内死亡的prob.) * (1 - 71岁一年内死亡的prob.) * 72岁一年内死亡的prob * 350,000

70岁不死的概率 71岁也不死的概率 72岁才死的概率

1 个答案

pzqa39 · 2024年10月16日

嗨,从没放弃的小努力你好:


这个方法是有问题的,死亡概率在每个年龄段都是基于前一个年龄段活下来的人的。例如,要算72岁死亡的概率,首先要计算出活过72岁之前每一年的生存概率。这就是为什么我们要用累积生存概率,而不是简单乘以每年的死亡概率。每个年龄段的死亡概率不仅仅是当年不死就行,而是需要考虑之前年龄段活下来的可能性。如果没有考虑累积生存概率,计算出的概率就不准确。

 

另外我也用同学的方法计算了一下答案,算出来是6388.5,虽然确实很接近答案,忽略累计生存概率之后的偏差也不是很大,但方法还是不够严谨。

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虽然现在很辛苦,但努力过的感觉真的很好,加油!