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lman · 2021年05月02日

Prospect theory VS. Expected utility theory

NO.PZ2015111901000007

问题如下:

The topic of another lecture is prospect theory. Liu presents the students with the following two situations and asks them if they would accept or reject each one:

Situation 1 A 50% probability of winning $10,000 and a 50% probability of losing $4,000

Situation 2 A 50% probability of winning $10,000 and a 50% probability of losing $8,000

The students vote to accept Situation 1 but reject Situation 2. Liu then presents a third situation:

Situation 3 Choosing between losing $12,000 with 100% certainty, or accept­ing a gamble that offers a 50% probability of winning $6,000 and a 50% probability of losing $24,000

The students vote to accept the gamble in Situation 3.


Explain how the voting results in each of the three situations are consistent with prospect theory.

i.Accepting Situation 1

ii.Rejecting Situation 2

iii.Accepting the gamble in Situation 3

选项:

解释:

Prospect theory is an alternative to expected utility theory. This theory describes how individuals make choices in situations in which they must decide between alternatives that involve risk and how they evaluate potential losses and gains. Prospect theory considers how alternatives are perceived based on their framing, how gains and losses are evaluated, and how uncertain outcomes are weighted.


i. Accepting Situation 1

Most people reject a gamble with even chances to win and lose unlessthe possible win is at least twice the size of the possible loss.

In this gamble, the possible win is 2.5 times the possible loss, so the student vote to accept Situation 1 is consistent with prospect theory. Accepting Situation 1 is consistent with prospect theory because experimental evidence shows that most people reject a gamble with even chances to win and lose, unless the possible win is at least twice the size of the possible loss.


ii.Rejecting Situation 2

Most people reject a gamble with even chances to win and lose unlessthe possible win is at least twice the size of the possible loss.

In Situation 2, the chances to win and lose are the same but the possible win is only 1.25 times the possible loss. Thus the student vote to reject Situation 2 is consistent with prospect theory.

Rejecting Situation 2 is consistent with prospect theory because experimental evidence shows that most people reject a gamble with even chances to win and lose, unless the possible win is at least twice the size of the possible loss. In Situation 2, the possible win is only 1.25 times the possible loss, so the student vote to reject the investment is consistent with prospect theory.


iii.Accepting the gamble in Situation 3

People are risk-seeking when there is a low probability of gains or a highprobability of losses.

Deviations in decision making result in overweighting low-probability outcomes.

The gamble may appear more attractive than the sure loss, so the student vote to accept the gamble is consistent with prospect theory. Experimental evidence shows that risk-seeking preferences are held by a large majority of people when there is a low probability of gains or a high probability of losses. Therefore, the student vote to accept the gamble over the sure loss in Situation 3 is consistent with prospect theory.

Expected utility theory讲的啥,理论太多,都忘了。是不是说人不管是在赚钱的时候,还是亏钱的时候都必须是风险厌恶?也就是理性人假设?

而Prospect theory发现人在赚钱的时候是风险厌恶,在亏钱的时候则是风险喜好。原因是因为亏钱给人带来的负面效用更大,所以人们甘愿承担更大的亏损风险以挽回损失,这也就导致了holding the losers too long。是这样么?


另外,Prospect theory和损失厌恶是一回事么?所以损失厌恶是Prospect theory的一部分?

1 个答案

王琛_品职助教 · 2021年05月05日

嗨,从没放弃的小努力你好:


1)Expected utility theory讲的啥,理论太多,都忘了。是不是说人不管是在赚钱的时候,还是亏钱的时候都必须是风险厌恶?也就是理性人假设?

Expected utility theory 通常假设个人是厌恶风险的

请参考:https://class.pzacademy.com/qa/75450


2)而Prospect theory发现人在赚钱的时候是风险厌恶,在亏钱的时候则是风险喜好。原因是因为亏钱给人带来的负面效用更大,所以人们甘愿承担更大的亏损风险以挽回损失,这也就导致了holding the losers too long。是这样么?

是的,loss aversion 在 loss 时继续持有股票,因为讨厌确定的亏损,想要搏一把,看看股价能不能涨上来。

这个是 loss 时,确定情况和不确定情况的对比


3)另外,Prospect theory和损失厌恶是一回事么?所以损失厌恶是Prospect theory的一部分?

可以理解为损失厌恶是 Prospect theory 的一部分

loss aversion 其实对应的是 prospect theory 的 value function 部分

请参考:https://class.pzacademy.com/qa/68320

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