Genius Economist

Marginal Revolution 今天介紹了一位天才經濟學家。年紀比我輕但是明年就要拿到Phd，而且已經有一篇很多人引述的論文。

他的名子叫Glen Weyl，研究方向跟我的興趣很相近。

Econ Concepts 12: 統計檢定的必要性

最近有一位NBA裁判涉嫌簽賭，造成體壇的轟動。而前一陣子，Wolfers 跟 Price 兩位經濟學家又發現NBA裁判有種族歧視之嫌疑。The Sports Economist post了一篇非常好的文章，可以提共給大家，同時這個post也強調了統計的重要性:

Astute economists here and elsewhere noted that the level of bias observed in the paper amounted to a maximum of .1 or .2 fouls per game per player, a number unlikely to be uncovered by even careful watching of games and video tapes. (Similarly, as noted in Moneyball, the difference between a .300 hitter and a .275 hitter is 1 base hit every two weeks. Hence, Billy Beane relies on his statisticians rather than his scouts.) Of course, the whole reason the field of inferential statistics has been developed is to help discover relationships that cannot be identified through casual (or even intense) direct observation. While there may be valid arguments why Price and Wolfers are wrong, the NBA's claim that "We can't see it with our naked eyes" was always ignorant in the extreme.

Now it comes out that one of the NBA's men in black was apparently on the take, a fact that went unnoticed by the NBA's trained observers until they got a call from the FBI. If the naked eye can't even pick up a guy trying to throw games for the mob, how can there be any hope, aside from well-designed statistical experiements like that of Price and Wolfers, of discovering subtle (and almost certainly, subconcious) racial bias in the NBA?

Emily Oster on AIDS in Africa

你認為你對非洲的愛滋病情況很瞭解嗎? 最近很紅的經濟學家Emily Oster要挑戰我們對愛滋所知道的幾件事。

沒時間看video的人，簡單而言:

1. 目前花很多錢在教育非洲人關於性病，這所能達到的效果有限。因為非洲人效用的現值(present value) 很低，沒有得愛滋的平均壽命太低了，所以得愛滋的機會成本不高。因此花這麼多錢在教育上，是無法達到我們的預期效果。

2. UN預測有 25 million愛滋病患，這數字太大了，Oster估計只有 5 million。

3. 貧窮造成愛滋病，因此讓他們開放貿易可以減少愛滋。這觀念有問題，至少在短期而言。在短期內，因為交易頻繁，性病的傳染途徑也增多，因此病例會增加。長期而言，(我認為啦!)，使他們變的富有一定能減少病例。

136th Open Championship

每一次在Carnoustie打英國公開賽，我都需要吃鎮定劑，因為這個球場帶給大家的drama不輸任何一本血脈噴張的小說。上一次在這邊打，我跟我家人在Denver度假，那個週末，小甘迺迪與他的妻子乘坐的小飛機墜機，所以第三天的賽事幾乎一直被 breaking news 打斷，那一天，一未不知名的法國佬領先群雄，打完三天贏大家6杆。他的名字叫Jean van de Velde，現在是家喻戶曉的高爾夫球選手，but for the wrong reasons。 再最後一天的最後一洞，他的六杆優勢已減為三杆，但是沒關係，最後一洞只要打double bogey 就可以贏，這連我都做得到! 但是一連串的錯誤選擇使他吞下triple bogey!! 最後在延長賽敗給另一未不知名的選手Paul Lawrie。至今Jean van de Velde再高爾夫球界已經變成一個常用的名詞，意思為 "笨的選擇"。例如，I pulled a Jean van de Velde on the 15th hole。就是我再第十五洞，做了一連串的idiotic moves。聽我講那麼多還不如欣賞以下的片段:

1. Van de Velde 自己解說
2. 老日幫他解釋

(Jean van de Velde 再最後一洞泡腳沉思，還好前一天有刮腿毛。令人痛心的loss。)

而今年的比賽不輸1999年的。先講Andres Romero，一位阿根廷新人，經驗不夠但是球技非常純熟。他最後一天打了十支birdie，只用了24推杆，但是也打了兩個double bogey，其中最傷的就是第17洞。那時他已經領先兩杆，第二杆從長草打出來時卻撞到想西的圍牆，彈到界外。Romero再最後一洞的par putt撞到洞口彈出來，若進的話，還可以打延長賽。但是他還年輕，未來我們還會在見到他。(另一未讓我刮目相看的是Rory McIlroy，這小子會紅。)

(推杆太強了，沒人能抵擋Romero的攻勢，除了最後兩洞。)


再來就是Harrington。Harrington長久以來就是我很喜歡的選手，Mr. Nice Guy。他在第14洞抓下老鷹，躍居領先榜上，到了最後一洞他領先Sergio Garcia一杆，但是他在那一洞卻下水兩次!! 讓大家想起 Jean van de Velde 的戲碼是不是又重新上演。他最後那一洞吞下double bogey，反而落後Sergio Garcia 一杆。但是故事還沒結束。

(Harringtony在想: 我應不應該跳進水裡泡腳學van de Velde? 還是不要好了，我昨天沒刮腿毛。)

Sergio Garcia 站在最後一洞的球道上，手拿著三號鐵，心想只要放在國嶺上兩推就好，但是他卻打到砂坑裡。但是沒關係，還是可以就par。十呎的par推杆離開杆頭時，就一直往洞前進，但是最後卻從洞的左邊lip out! Sergio Garcia，從他18歲時就被譽為會拿下許多大賽冠軍的選手，還需要再打四洞的playoff才能贏。這位西班牙選手，剛出來時，有一點自大，帶著小孩子氣，揚言要跟老虎伍茲PK，但是事隔8年，他仍然沒贏過大賽，也還沒長大，那小孩子氣已經不可愛了，反而惹人厭。他是我最討厭的選手!

Evidence that Sergio is spoiled(大baby要哭了嗎? 都是老天爺的錯! 他又輸了。)

最後，Harrington在延長賽脫穎而出，贏的他的第一做大賽! There is a God!

(Deserving Open Champion，Padraig Harrington!)

(Yeah Baby!)

我前幾天到哪去了?

我前幾天去參加這個東西: FEMES

我不久後會將一些趣事跟心得跟大家分享，但是請給我一點時間。

Tiger Teasing Roger

Tiger shows some class in this Nike ad

An Economic Question: Buying Furniture

我昨天去買書櫃。我到家具店的現場看家具。我看上一個有門的，四層的。標價5500，但是我連殺價都沒殺，老闆就馬上說賣我750。我目瞪口呆，原本要殺價的心情完全被他毀了。

'請問為何要賣我那麼便宜?' 是一個很直覺的反應。但是應該問 '為何標價那麼高?'。所以我問大家，為何標價那麼高?

Econ Concepts 11: Incomplete Contracts

這是我寫的期末報告的Intro的一部份:

Incomplete contract has slowly become one of the hottest topics in microeconomics. It differs from previous approaches because it looks at a restricted set of contracts, usually much simpler. While previous approaches focus on optimizing over a general set of contracts subject to incentive and participation constraints (such an approach is conveniently called complete contracts), the incomplete approach restricts its search of contracts over an admittedly smaller set of contracts. In the end, the simpler contracts often can only specify property rights and control rights. An example will help distinguish these two approaches, and the different issues it focuses on.

One of the simplest and most researched topics in asymmetric information is CEO compensation. The complete contracts approach calls on us to focus on finding an optimal compensation package, such that under this package, the CEO’s incentives are aligned with the stockholders. As a result, it is in the best interest of the CEO to work ‘hard’ for the stockholders. The incentive package that we find using this method is often complex and seldom seen in the real world. There are also other practical implications that do not seem to abide to the observations in the real world. One of the most obvious is that under complete contracts, the two parties, the CEO and the stockholders, never have to renegotiate the terms of the incentive package. Since after offering the incentive package, the stockholders do not have to worry that the CEO will do something that is ‘not’ in their best interest.

Under the incomplete contracts approach, other factors become important, and these factors are often institution related. Continuing with our CEO compensation example, it is obvious that the stockholder’s decision making procedure or the amount of control the stockholders have over the CEO’s decision are also very important.

As a result, the incomplete contracts approach shifts its focus from compensation and incentive inducing issues to institutional and procedural issues. The change in methodology has spawned a rich body of research in industrial organization, corporate finance, and other areas of economics. It has helped make theories more realistic.

However, questions still remain, if a complete contract can be written, then why would anyone write an incomplete one? Several answers have been provided, but all can be classified into three distinct reasons:

1.
Writing contracts is costly. If under the supervision of a lawyer, a payment must be made to the lawyer for each word the lawyer writes, then both parties may neglect to hire a lawyer, or hire one but write up a simpler contract than one without cost.

2. Sometimes states of the world are too complicated to describe and are unable to be included in the contract simply because we can not foresee future
events.

3. Many aspects of the relationship are observable to both parties but are unverifiable to an impartial third party, such as the court. Under these circumstances, the contract is naturally incomplete, since even if such aspects are included, it wouldn’t help when a dispute arises, because an impartial third party will not be able to determine the truthfulness of their claims. Note that this is different from the traditional moral hazard problem. Previous moral hazard problem treated CEO effort as an unobservable variable, but if it was observed, the stockholders can include effort level in the contract. Incomplete contracts treat this problem differently, even if effort is observed, it can’t be included in the contract because it couldn’t be verified by an impartial third party.

大學升碩士的閱讀物

通常大學畢業後，大部分的人都沒心情唸書。但是若你像我，以下幾本是可以幫忙準備經研所的工具。(至少這是我的計畫啦!) 能看多少就看多少，拿消化多少就消化多少。

Math:
1. 數學不用就馬上忘記，複習的最佳夥伴: Alpha Chiang - Fundamental Methods of Mathematical Economics

2. 實變: Efe Ok - Real Analysis with Economic Applications

Microeconomics:
1. 複習 Microeconomic Theory: Philip Reny and Geoffrey Jehle - Advanced Microeconomic Theory

2. 產業組織: Jean Tirole - The Theory of Industrial Organization

3. 賽局: Martin Osborne and Ariel Rubenstien - A Course in Game Theory

Macroeconomics:
1. 複習大學 Macro : Robert Barro - Macroeconomics

2. Economic Growth : Robert Barro and Xavier Sala I Martin - Economic Growth

Econometrics:
1. 複習數統兼融合觀念: Takeshi Amemiya - Introduction to Statistics and Econometrics