2015年3月16日 星期一

Paul Krugman

  Paul Krugman 是紐約時報的專欄架作家。
紐約時報中文版現在免費。
從70年代起,就有諾貝爾獎得主在Newsweek等等刊物,當起專欄作家呢.....


Ouch.
Nobel laureate Paul Krugman is way off when he accuses the Swedish central...
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專欄作者

奧巴馬的新氣候行動計劃有利於美國經濟


本周,投票權、同性婚姻和寶拉·迪恩(Paula Deen)事件讓新聞界相當忙碌。即便如此,新聞媒體對奧巴馬總統新的「氣候行動計劃」的關注之少,仍然令人驚訝。你當然可以無視他公開這個計劃時發表的 出色講話,但這一計劃還是非常重要。這一次,奧巴馬不再鼓吹立法了,我們都知道這通不過。相反地,他的新計劃將依靠行政措施。這就意味着,該計劃跟我們應 對氣候變化的早期舉措不一樣,它可以繞過控制眾議院的反環保主義者。
共和黨人意識到了這一點,他們正在沮喪地捶胸頓足。而他們 所能做的,似乎也就是強烈抗議了(也許還會恐嚇政府,令它妥協)。然而,有趣的是,現在他們似乎並不熱衷於攻擊氣候科學,也許是因為那樣做會讓他們聽上去 不講道理(他們本來就是)。現在他們轉而從經濟角度出發,譴責奧巴馬政府發動了一場會減少就業崗位的「煤炭戰爭」。
其實,他們也沒有完全說錯。從某種程度而言,奧巴馬的新計劃就是在對煤炭開戰——因為所有認真想減少溫室氣體排放的措施,都必然會要求減少煤炭的使用量。但是,向煤炭開戰並不會減少就業崗位。事實上,認真為溫室氣體排放立新規,可能正好是美國經濟所需要的。
那麼,要怎麼做呢?首先,奧巴馬錶示他打算利用國家環境保 護局(Environmental Protection Agency)的影響力,對電廠的碳排放加以限制。這類電廠不是溫室氣體的唯一來源,但它們的排放量的確佔到了總排放的約40%。而且,監管發電廠的排放 量本來就是一個標準做法,我們已經制定了一些政策來限制這些工廠排放的其他污染物,比如二氧化硫和汞,所以把碳加到這個名單里也不算是太離譜,至少原則上 不算。
但是,對碳排放進行限制不是會提高電力成本嗎?那不就會減少就業崗位嗎?答案是:「是」也「不是」。
是的,實行新的碳排放規則會增加發電成本。電力公司可能會關閉一些舊的燃煤電廠,轉向成本更高的低排放替代發電方式 —— 部分是可再生能源,比如風力,但主要還是使用天然氣。此外,為了取代舊的燃煤電廠,他們將不得不投建新產能。
事實上,所有這些都會導致電費的增加——不過遠沒有人們通 常認為的那麼多。其實這有點搞笑:右翼人士喜歡頌揚自由市場的力量,聲稱私營企業可以應付任何問題,但是,他們然後又掉過頭來堅稱私營企業將會絕望地舉手 投降,在新規則的面前崩潰。真正的歷史經驗 ——例如,從保護臭氧層和減少酸雨等行動中得出的經驗 —— 是這樣的:只要監管條例比較靈活,企業可以採取創新的解決方案,它們減少排放量的成本通常比你以為的要低廉得多。
儘管如此,這也還會有一定的成本。這難道不會減少就業崗位嗎?實際上不會。
我們一定要記住,目前影響美國經濟的不是產能不足,而是需求不足。房地產市場的不景氣,家庭債務的威脅,削減公共開支的錯誤時機,這些都導致了這樣一種局面:誰都不想花錢;由於你的支出就是我的收入,我的支出就是你的收入,這就造成了整體經濟的不景氣。
迫使電力行業改進其操作又怎麼會導致這種情況的惡化呢?它不會,因為產能不足和成本都不是當前經濟的制約因素。
而且,正如我已經提到的,環保行動實際上可能會發揮積極的作用。假設電力公司為了適應這個新規則,決定關閉一些現有發電廠,並投資修建新的、低排放的產能。那麼這就是一種支出的增加,而我們的經濟需要的,正好就是更多的支出。
當然,上述情況究竟會不會發生仍不清楚。我認識的一些人對這個新的氣候計劃心存懷疑,覺得奧巴馬不會真的落實貫徹它。對此我只能說,我希望是他們錯了。
奧巴馬在發言接近尾聲時,鼓勵聽眾們說:「要投資。要剝 離。要提醒大家,良好的環境和強勁的經濟增長並不矛盾。」通常人們對這種說法不太買賬,認為它是逃避艱難選擇的借口。但這一次,它純粹是對形勢的良好把 握:我們真的可以投資新能源,剝離舊能源,同時促進經濟的更強發展。那麼,就讓我們行動起來吧。
翻譯:楊洋


2013年 05月 27日 16:05

Reinhart and Rogoff to Krugman: ‘Spectacularly Uncivil Behavior’

 The gloves are off in the roiling academic dispute over the merits of austerity and the dangers of debt.

In the latest round, Harvard economists Kenneth Rogoff and Carmen Reinhart accused Princeton economist and New York Times columnist Paul Krugman of “spectacularly uncivil behavior” and the inaccurate allegation that they refused to share data supporting their work linking heavy debt levels to subsequent slow economic growth.

Papers such as Mr. Rogoff and Ms. Reinhart’s, which warn of the perils of too much government debt, “haven’t just lost their canonized status, they’ve become the objects of much ridicule,” Mr. Krugman wrote in a recent New York Review of Books attack on advocates of austerity.

“Despite their paper’s influence, Reinhart and Rogoff had not made their data widely available─and researchers working with seemingly comparable data hadn’t been able to reproduce their results,” Mr. Krugman wrote.

Mr. Rogoff and Ms. Reinhart responded Sunday in a five-page letter and a four-page appendix to Mr. Krugman, posted on their website:

“We admire your past scholarly work, which influences us to this day. So it has been with deep disappointment that we have experienced your spectacularly uncivil behavior the past few weeks,” the letter said. “You have attacked us in very personal terms, virtually nonstop, in your New York Times column and blog posts. Now you have doubled down in the New York Review of Books, adding the accusation we didn’t share our data.”

The data in question were used in a body of research by Mr. Rogoff and Ms. Reinhart, including their seminal 2010 paper, “Growth in a Time of Debt.” That paper concluded that during the post-World War II era, levels of public debt above 90% of a country’s gross domestic product generally translate into years of slow growth.

The data used to support their thesis included country figures on real gross domestic product, as well as debt to GDP. The 2010 paper─along with other works by Mr. Rogoff and Mr. Reinhart─were cited by austerity advocates as a justification for ratcheting back public spending after the financial crisis.

The findings came under a cloud last month. Thomas Herndon, a graduate student at the University of Massachusetts Amherst, found a spreadsheet error in the Rogoff-Reinhart calculations in attempting to replicate the paper for an econometrics homework exercise. Mr. Herndon published his findings with two UMass Amherst professors, Robert Pollin and Michael Ash.

Mr. Rogoff and Ms. Reinhart conceded the spreadsheet error but stood by their findings. Early this month, they published on their website a correction to the 2010 paper.

The challenge to a bedrock of post-crisis austerity policy-making had an immediate and global effect. The Rogoff-Reinhart research had made a strong argument for promptly cutting government spending and chipping away at deficits. Mr. Krugman has long attacked this line of thought, warning that curbing government spending now is likely to hinder the economic recovery.

The UMass Amherst paper sparked a world-wide rethink of austerity policies. In recent weeks, Mr. Rogoff and Mr. Reinhart have found themselves squaring off not just with a 28-year-old doctoral student, but also with a Nobel Prize winner in Mr. Krugman.

“Not surprisingly, Reinhart and Rogoff have tried to defend their work; but their responses have been weak at best, evasive at worst,” Mr. Krugman wrote in the New York Review of Books. “Notably, they continue to write in a way that suggests, without stating outright, that debt at 90% of GDP is some kind of threshold at which bad things happen.”

Mr. Rogoff and Ms. Reinhart in their letter told Mr. Krugman, “Your characterization of our work and our policy impact is selective and shallow. It is deeply misleading about where we stand on the issues.”

They also wrote that the UMass Amherst paper “reinforces our core result that high levels of debt are associated with lower growth.” And they said “the accusation in the New York Review of Books” that they had failed to share their data earlier is “a sloppy neglect on your part to check the facts before charging us with a serious academic ethical infraction” and “an unfounded attack on our academic and personal integrity.” The debt and GDP data, they said, have been available on their website since 2010.

Mr. Herndon’s recollection meshes in part with that of Mr. Rogoff and Ms. Reinhart. On Sunday, he recalled accessing debt and GDP data for his replication exercise either directly from the authors’ website or from links on the site. However, Mr. Herndon─who began his attempt to replicate the Rogoff-Reinhart findings in the fall of 2012─noted that he didn’t receive the authors’ spreadsheet─a key piece of his replication exercise and one that revealed the Excel glitch─until early last month. In short, he found some of the data on their web site, but not enough to complete a full replication.

The public challenge to the authors has raised “important issues…over the past few weeks,” for economists, said Justin Wolfers, of the University of Michigan. The dispute, which rippled across the Internet over the weekend, has underscored “the importance of replication in economics,” he said.

On Sunday, Mr. Krugman responded with two posts, including one titled “Reinhart and Rogoff Are Not Happy.”

“This could go on forever, and both they and I have other things to do,” he wrote, adding that he thinks Rogoff and Reinhart have some explaining to do about the relationship between the 90% threshold and growth.

There is “an enormous difference between the statement ‘countries with debt over 90% of GDP tend to have slower growth than countries with debt below 90% of GDP’ and the statement ‘growth drops off sharply when debt exceeds 90% of GDP’. The former statement is true; the latter isn’t. Yet R&R have repeatedly blurred that distinction,” he wrote.

Brenda Cronin
2013年 05月 27日 16:05

哈佛經濟學家炮轟克魯格曼“不文明”


政府實施緊縮政策的好處以及背負債務的危險方面﹐學術界存在莫大爭議。而現在﹐爭議雙方開始動真格的了。

在 最新一輪“對峙”中﹐哈佛大學經濟學家羅戈夫(Kenneth Rogoff)和萊因哈特(Carmen Reinhart)指責普林斯頓大學經濟學家、《紐約時報》(New York Times)專欄作家克魯格曼(Paul Krugman)不僅行為極其不文明﹐並且言論也有失準確。克魯格曼曾說﹐羅戈夫和萊因哈特拒絕分享支持其研究成果的數據。他倆研究的是一國政府沉重的債 務負擔與之後緩慢的經濟增長之間的關係。


Bloomberg News
克魯格曼。照片拍攝於今年1月。
克魯格曼前不久在《紐約書評》(New York Review of Books)上發表的一篇批評緊縮政策倡導者的文章說:羅戈夫和萊因哈特等人的論文不僅失去了備受推崇的地位﹐還成了被嘲弄的對象。這些論文警告稱﹐負債過多會使政府處於危險境地。

克魯格曼寫道:儘管他們的論文有一定的影響力﹐但萊因哈特和羅戈夫之前沒有公佈他們的數據﹐而採用表面上與之相當的數據的研究人員未能得出與他們同樣的結果。

羅戈夫和萊因哈特週日回應了克魯格曼﹐在他們的網站上公佈了一份長達五頁的信函和四頁的附件。

信件說:我們欽佩您以前的學術成就﹐至今我們都還受其影響﹐也正因如此﹐您在過去幾週引人矚目的不文明行為才會讓我們大失所望。信件說:您在《紐約時報》專欄和博客文章里對我們展開了幾乎不停歇的人身攻擊﹐現在又通過《紐約書評》來加大炮轟力度﹐還指責我們沒有分享數據。

文 中所說的數據是羅戈夫和萊因哈特在某個研究機構中用過的數據﹐包括他們在2010年發表的那篇意義重大的論文《債務時代下的增長》(Growth in a Time of Debt)。該論文的結論是﹐二戰後﹐如果一個國家公共債務佔國內生產總值(GDP)的比重超過90%﹐基本上會導致這個國家進入緩慢增長。

在那篇論文中﹐用於支持其觀點的數據包括一些國家的實際GDP以及債務與GDP的比重等。緊縮政策倡導者以這篇2010年的論文及羅戈夫與萊因哈特的其它研究成果當作是經濟危機後政府應縮減公共支出的理由。

這 些研究結果上個月受到質疑。馬薩諸塞大學阿姆赫斯特分校(University of Massachusetts Amherst)研究生赫恩登(Thomas Herndon)有一次做計量經濟學作業時試圖復製羅戈夫和萊因哈特這篇論文的結果﹐卻發現他們倆的計算有表格錯誤。赫恩登將他與該校兩名教授波林 (Robert Pollin)和阿什(Michael Ash)的發現公開了出來。

羅戈夫和萊因哈特承認了這一表格錯誤﹐但仍力挺原先的研究結果。本月初﹐他們在網站上公佈了對2010年那篇論文的修正。

對戰後緊縮政策制定原理的挑戰收到了立竿見影的效果﹐而且在世界範圍內都產生了影響。羅戈夫和萊因哈特的研究成果曾是立即削減政府開支和減少赤字的有力論據。克魯格曼則一直批評這個想法。他警告稱﹐限制政府開支可能會阻礙經濟復蘇。

馬薩諸塞大學阿姆赫斯特分校師生最近發表的這篇論文﹐在全球範圍內引發了對緊縮政策的反思。羅戈夫與萊茵哈特最近幾週發現向他們挑戰的不僅有一名28歲的博士研究生﹐還有諾貝爾獎獲得者克魯格曼。

克 魯格曼在《紐約書評》中說﹐萊茵哈特與羅戈夫試圖為自己的研究成果辯護﹐這並不出人意料﹔但他們的回應往好說是蒼白無力的﹐往壞說則是一味回避要害問題。 克魯格曼說﹐他們顯然繼續在回應文章中暗示﹐一個國家的公共債務如果超過其GDP的90%﹐那就意味著它突破了某個閾值﹐此後一系列壞事將接踵而至﹐雖然 他們並沒有直率地將這一觀點表達出來。

羅戈夫與萊茵哈特在信中對克魯格曼說﹐你對我們研究成果和政策影響的描述是有選擇性和膚淺的﹐嚴重誤導了外界對我們所持立場的看法。

他 們還寫道﹐馬薩諸塞大學阿姆赫斯特分校師生的論文強化了我們核心的研究結論﹐即高負債水平是與經濟增長率降低相伴出現的。他們還說﹐克魯格曼在《紐約書 評》中指責他們二人此前沒能與外界分享其數據﹐這種行為是在草率忽略了對事實加以核對的情況下指責他們嚴重違背學術道德﹐是對他們二人學術和個人聲譽的無 端攻擊。羅戈夫與萊茵哈特說﹐2010年以來在他們的網站上就可以查到他們在研究中所用的債務和GDP數據。

馬薩諸塞大學阿姆赫斯特分校 研究生赫恩登的回憶一定程度上與羅戈夫和萊茵哈特的這一說法相吻合。他週日回憶說﹐上個月自己在做驗證羅戈夫和萊茵哈特那項研究結論的練習時﹐不是直接從 這兩人的網站上獲得了相關債務和GDP數據﹐就是從與這一網站的鏈接中獲得了這些數據。但赫恩登也指出﹐在上月初之前他沒有看到羅戈夫和萊茵哈特的電子數 據表。赫恩登從2012年秋起就試圖驗證羅戈夫和萊茵哈特那項研究的結論﹐而這份電子數據表是他做這項驗證練習時所需的一份重要資料﹐該數據表顯示羅戈夫 和萊茵哈特的Excel表格中有一個計算錯誤。簡而言之﹐赫恩登的確從羅戈夫與萊茵哈特的網站上找到了一些數據﹐但這些數據還不足以讓他通過自己的研究證 明羅戈夫與萊茵哈特當年的結論是正確的。

密歇根大學(University of Michigan)的沃爾弗斯(Justin Wolfers)說﹐過去幾週中﹐這一對於羅戈夫與萊茵哈特的公開挑戰把一些重要問題展示在經濟學家們面前。他說﹐相關爭論週末期間在互聯網上產生了反響 ﹐這一爭論彰顯出在經濟學領域對以往研究成果進行驗證性研究的重要性。

克魯格曼週日在網上發了兩個帖子以回應羅戈夫與萊茵哈特對他的批評﹐其中一篇的題目是《萊茵哈特與羅戈夫不高興》(Reinhart and Rogoff Are Not Happy)。

他在文中寫道﹐這事有可能沒完沒了地繼續下去﹐他們二人和我都有其他事要做。克魯格曼還說﹐他認為羅戈夫與萊茵哈特需要對公共債務達到GDP的90%與經濟增長的關係多做一些解釋。

他 寫道﹐“公共債務佔GDP的比重超過90%的國家﹐其經濟增長率往往會慢於公共債務佔GDP的比重不足90%的國家”這一說法﹐與“當一個國家的公共債務 佔GDP的比重超過90%時﹐其經濟增長率會大幅下降”這種說法存在巨大不同。前一種說法是對的﹐後一種則不是﹐但羅戈夫與萊茵哈特一再模糊這兩種說法間 的區別。

Brenda Cronin



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