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SUN · 2020年12月02日

问一道题: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.

这道题1和2的对比是不是说明行为金融里面普通人的做法也是正确的??

2 个答案
已采纳答案

Olive_品职助教 · 2020年12月04日

“ 就是没有bias ”


有没有bias要看一个理性人怎么选,对于一个理性人而言,损失带来的效用减少和收益带来的效用增加应该是相等的值。不会更看重损失或者更看重收益。

所以在选择是否gamble的时候应该完全基于【这个gamble带来的期望收益是否大于不gamble的情况】。

Situation 1,不gamble一毛钱没有,gamble的期望收益是3000,所以仅仅基于期望收益,肯定要选gamble。

Situation 2,不gamble一毛钱没有,gamble的期望收益是1000,所以仅仅基于期望收益,肯定要选gamble。

上面这是理性人应该做的选择,但是实际上人们没有这么选,说明是有bias的。

SUN · 2020年12月04日

明白了,谢谢

Olive_品职助教 · 2020年12月03日

嗨,努力学习的PZer你好:


不太明白你说的【正确的】是什么标准。1和2对比是在考查一个实证研究的结论,即

  • 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.  

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