Tuesday, April 24, 2007

單身漢的天堂! The importance of Common Knowledge

有一個村莊住100對夫妻。村裡的100個男的都會每一星期聚會,若家裡的妻子守貞潔,先生就會誇讚她。若家裡的妻子有外遇,先生就會抱頭痛哭。

但是每一個女的都有外遇,而每一個男的都知道,但是都以為自己的妻子沒有外遇。所以每一星期的聚會都在讚美聲中度過。

直到有一天一位智者路過,在村莊休息。他觀察了一星期後,他決定參加男人每一星期的聚會。在聚會上,他看到所有100個男的讚頌自己的妻子。

他最後就說: "這村裡有一個女的有外遇"

過了一星期後,所有100個男的繼續讚美自己的妻子。這持續了99星期。但是到了第100個星期,所有的男的都抱頭痛哭。

請問為什麼會這樣?

Thursday, April 19, 2007

What is New in the World of Econ: Part 4 - 男女大不同

現在的社會強調兩性平等,

但是社會裡的種種現象往往使我們懷疑這機制是否真的平等。

我們是可以懷疑制度或社會機制的問題,

但是若女性跟男性在行為上本來就有很大的差異呢?

這樣一來就很有可能造成看似不"平等"的結果了。

最近有一篇論文做實驗,測試男性與女性在選擇上的差異。

這一篇論文很特別,實驗在經濟學是非常罕見的,但是近幾年來越來越熱門。

他是如何進行實驗呢?:

首先他們將兩個女的跟兩個男的分到一組,

再叫他們做一些簡單的數學運算(國小程度的)當做練習,

練習完後,四個人可以個別單獨選擇玩 "保守遊戲" 或是 "野心遊戲" (詞窮!)

選擇"保守"的人只要答對一題,無論如何都可以拿0.50塊錢。

選擇"野心"的人答對一題拿2塊錢,只有在他是四個人當中答對最多題時才可以拿錢,

若不是選擇野心者就無法拿到錢。

實驗結果發現75%的男性選擇"野心",而只有百分之25的女性選擇"野心"

這代表男性高估自己的實力(自以為比全部的人都強),而女性卻低估。

這結果有許多implication。我想CEO是男性比較多可能跟這有關。

Monday, April 16, 2007

What is New in the World of Econ: Part 3 - Happy Doing Business with You!

曾經想過再哪一個國家經商最便利嗎?World Bank 有做調查,以十個項目當衡量標準:

Starting a Business

Dealing with Licenses

Employing Workers

Registering Property

Getting Credit

Protecting Investors

Paying Taxes

Trading Across Borders

Enforcing Contracts

Closing a Business

以下是經商便利排行的前十名:

Singapore

New Zealand

United States

Canada

Hong Kong, China

United Kingdom

Denmark

Australia

Norway

Ireland

台灣在哪呢?

去找找看吧

Sunday, April 15, 2007

Phenomenons on Planet Econ: Part 3 - Disclosure

這世界很奇妙! 你有可能是一位很勤快的工人,能力像當強,但是除非你真的實際下去工作了,老闆才能知道你的超強能力,所以你有可能面試時就被刷了。這時signaling就派上用場了。

但是若我們今天講的是你去申請保險的事? 要證明你很健康比證明你工作能力強簡單許多,只要拿出體檢結果就行了! 而保險公司要確認也不難。

假設今天政府說個人健康資料是私人資料,因此對方無法迫使你提供你的健康資料。這時就有兩個問題了:
1. 若不再加其他法律規範,這個法條有用嗎?
2. 若要加法條,要加什麼?

1. 這個法條沒有用。因為健康的人還是會提供健康資料,而當你不提供人家就知道你不健康。所以不健康的人還是沒保護到。
2. 若要保護不健康的人,就要全面禁止提供健康資料。

這個例子相當有趣。而他背後的理論就是Grossman and Hart的Full Disclusure Theorem。

Tuesday, April 03, 2007

社會學家看經濟學家

經濟學家就是社會學家阿! 是嗎?

沒錯,但是似乎社會學家認為經濟學家跟他們不太像。為何呢? 因為最近有幾位社會學家對經濟學家的生態非常感興趣(若他們認為經濟學家跟他們一樣,就不會研究我們)

其中一位的研究結果顯示:"…most of their knowledge is too abstract to be of much substantive use, andtheir standards of academic rigor may play only a minor role in legitimizingtheir day to day authority."

意思就是經濟學家的研究都太抽象(太數學),而這麼做只是在建立他們在象牙塔內的勢力一小部分的作為。(我照我自己的意思翻)

另一位柏克萊學者說:"Scientific representations, policy paradigms, and internationallinkages all enter the competitive processes whereby different segmentsand groups in the various national economics professions seek to asserttheir authority on particular jurisdictions (professional, scientific, orpolitical)..."

意思就是"美式"的經濟學已成為影響其他國家的一個重要工具。而經濟學界也利用這一點來擴張自己的勢力。

我對這些東西沒意見,只是覺得很好玩。

Monday, April 02, 2007

有趣的故事

Suppose that every day, ten men go out for beer and the bill for all ten comes to $100.

If they paid their bill the way we pay our taxes, it would go something like this:

The first four men (the poorest) would pay nothing.
The fifth would pay $1.
The sixth would pay $3.
The seventh would pay $7.
The eighth would pay $12.
The ninth would pay $18.
The tenth man (the richest) would pay $59.So, that's what they decided to do.

The ten men drank in the bar every day and seemed quite happy with the arrangement, until one day, the owner threw them a curve. "Since you are all such good customers," he said, "I'm going to reduce the cost of your daily beer by $20." Drinks for the ten now cost just $80.
The group still wanted to pay their bill the way we pay our taxes so the first four men were unaffected. They would still drink for free. But what about the other six men - the paying customers? How could they divide the $20 windfall so that everyone would get his 'fair share?' They realized that $20 divided by six is $3.33. But if they subtracted that from everybody's share, then the fifth man and the sixth man would each end up being paid to drink his beer. So, the bar owner suggested that it would be fair to reduce each man's bill by roughly the same amount, and he proceeded to work out the amounts each should pay. And so:

The fifth man, like the first four, now paid nothing (100% savings).
The sixth now paid $2 instead of $3 (33%savings).
The seventh now pay $5 instead of $7 (28%savings).
The eighth now paid $9 instead of $12 (25% savings).
The ninth now paid $14 instead of $18 (22% savings).
The tenth now paid $49 instead of $59 (16% savings).

Each of the six was better off than before. And the first four continued to drink for free. But once outside the restaurant, the men began to compare their savings.

"I only got a dollar out of the $20," declared the sixth man. He pointed to the tenth man," but he got $10!""Yeah, that's right," exclaimed the fifth man. "I only saved a dollar, too. It's unfair that he got ten times more than I!"

"That's true!" shouted the seventh man. "Why should he get $10 back when I got only two? The wealthy get all the breaks!"

"Wait a minute," yelled the first four men in unison. "We didn't get anything at all. The system exploits the poor!"

The nine men surrounded the tenth and beat him up.

The next night the tenth man didn't show up for drinks, so the nine sat down and had beers without him. But when it came time to pay the bill, they discovered something important. They didn't have enough money between all of them for even half of the bill!

And that, boys and girls, journalists and college professors, is how our tax system works. The people who pay the highest taxes get the most benefit from a tax reduction. Tax them too much, attack them for being wealthy, and they just may not show up anymore. In fact, they might start drinking overseas where the atmosphere is somewhat friendlier.

這故事還蠻有趣的