Affichage des articles dont le libellé est PIB. Afficher tous les articles
Affichage des articles dont le libellé est PIB. Afficher tous les articles

samedi 27 avril 2013

The 1 Percent’s Solution

By
Source: nytimes.com, April 25, 2013

Economic debates rarely end with a T.K.O. But the great policy debate of recent years between Keynesians, who advocate sustaining and, indeed, increasing government spending in a depression, and austerians, who demand immediate spending cuts, comes close — at least in the world of ideas. At this point, the austerian position has imploded; not only have its predictions about the real world failed completely, but the academic research invoked to support that position has turned out to be riddled with errors, omissions and dubious statistics.


Fred R. Conrad/The New York Times
Paul Krugman
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Yet two big questions remain. First, how did austerity doctrine become so influential in the first place? Second, will policy change at all now that crucial austerian claims have become fodder for late-night comics?
      
On the first question: the dominance of austerians in influential circles should disturb anyone who likes to believe that policy is based on, or even strongly influenced by, actual evidence. After all, the two main studies providing the alleged intellectual justification for austerity — Alberto Alesina and Silvia Ardagna on “expansionary austerity” and Carmen Reinhart and Kenneth Rogoff on the dangerous debt “threshold” at 90 percent of G.D.P. — faced withering criticism almost as soon as they came out.
       
And the studies did not hold up under scrutiny. By late 2010, the International Monetary Fund had reworked Alesina-Ardagna with better data and reversed their findings, while many economists raised fundamental questions about Reinhart-Rogoff long before we knew about the famous Excel error. Meanwhile, real-world events — stagnation in Ireland, the original poster child for austerity, falling interest rates in the United States, which was supposed to be facing an imminent fiscal crisis — quickly made nonsense of austerian predictions.
       
Yet austerity maintained and even strengthened its grip on elite opinion. Why?
       
Part of the answer surely lies in the widespread desire to see economics as a morality play, to make it a tale of excess and its consequences. We lived beyond our means, the story goes, and now we’re paying the inevitable price. Economists can explain ad nauseam that this is wrong, that the reason we have mass unemployment isn’t that we spent too much in the past but that we’re spending too little now, and that this problem can and should be solved. No matter; many people have a visceral sense that we sinned and must seek redemption through suffering — and neither economic argument nor the observation that the people now suffering aren’t at all the same people who sinned during the bubble years makes much of a dent.
       
But it’s not just a matter of emotion versus logic. You can’t understand the influence of austerity doctrine without talking about class and inequality.
       
What, after all, do people want from economic policy? The answer, it turns out, is that it depends on which people you ask — a point documented in a recent research paper by the political scientists Benjamin Page, Larry Bartels and Jason Seawright. The paper compares the policy preferences of ordinary Americans with those of the very wealthy, and the results are eye-opening.
       
Thus, the average American is somewhat worried about budget deficits, which is no surprise given the constant barrage of deficit scare stories in the news media, but the wealthy, by a large majority, regard deficits as the most important problem we face. And how should the budget deficit be brought down? The wealthy favor cutting federal spending on health care and Social Security — that is, “entitlements” — while the public at large actually wants to see spending on those programs rise.
       
You get the idea: The austerity agenda looks a lot like a simple expression of upper-class preferences, wrapped in a facade of academic rigor. What the top 1 percent wants becomes what economic science says we must do.
       
Does a continuing depression actually serve the interests of the wealthy? That’s doubtful, since a booming economy is generally good for almost everyone. What is true, however, is that the years since we turned to austerity have been dismal for workers but not at all bad for the wealthy, who have benefited from surging profits and stock prices even as long-term unemployment festers. The 1 percent may not actually want a weak economy, but they’re doing well enough to indulge their prejudices.
       
And this makes one wonder how much difference the intellectual collapse of the austerian position will actually make. To the extent that we have policy of the 1 percent, by the 1 percent, for the 1 percent, won’t we just see new justifications for the same old policies ?
       
I hope not; I’d like to believe that ideas and evidence matter, at least a bit. Otherwise, what am I doing with my life? But I guess we’ll see just how much cynicism is justified.

The Excel Depression

By
Source: nytimes.com, April 18, 2013

In this age of information, math errors can lead to disaster. NASA’s Mars Orbiter crashed because engineers forgot to convert to metric measurements; JPMorgan Chase’s “London Whale” venture went bad in part because modelers divided by a sum instead of an average. So, did an Excel coding error destroy the economies of the Western world?

The story so far: At the beginning of 2010, two Harvard economists, Carmen Reinhart and Kenneth Rogoff, circulated a paper, “Growth in a Time of Debt,” that purported to identify a critical “threshold,” a tipping point, for government indebtedness. Once debt exceeds 90 percent of gross domestic product, they claimed, economic growth drops off sharply.
       
Ms. Reinhart and Mr. Rogoff had credibility thanks to a widely admired earlier book on the history of financial crises, and their timing was impeccable. The paper came out just after Greece went into crisis and played right into the desire of many officials to “pivot” from stimulus to austerity. As a result, the paper instantly became famous; it was, and is, surely the most influential economic analysis of recent years.
       
In fact, Reinhart-Rogoff quickly achieved almost sacred status among self-proclaimed guardians of fiscal responsibility; their tipping-point claim was treated not as a disputed hypothesis but as unquestioned fact. For example, a Washington Post editorial earlier this year warned against any relaxation on the deficit front, because we are “dangerously near the 90 percent mark that economists regard as a threat to sustainable economic growth.” Notice the phrasing: “economists,” not “some economists,” let alone “some economists, vigorously disputed by other economists with equally good credentials,” which was the reality.
       
For the truth is that Reinhart-Rogoff faced substantial criticism from the start, and the controversy grew over time. As soon as the paper was released, many economists pointed out that a negative correlation between debt and economic performance need not mean that high debt causes low growth. It could just as easily be the other way around, with poor economic performance leading to high debt. Indeed, that’s obviously the case for Japan, which went deep into debt only after its growth collapsed in the early 1990s.
       
Over time, another problem emerged: Other researchers, using seemingly comparable data on debt and growth, couldn’t replicate the Reinhart-Rogoff results. They typically found some correlation between high debt and slow growth — but nothing that looked like a tipping point at 90 percent or, indeed, any particular level of debt.
       
Finally, Ms. Reinhart and Mr. Rogoff allowed researchers at the University of Massachusetts to look at their original spreadsheet — and the mystery of the irreproducible results was solved. First, they omitted some data; second, they used unusual and highly questionable statistical procedures; and finally, yes, they made an Excel coding error. Correct these oddities and errors, and you get what other researchers have found: some correlation between high debt and slow growth, with no indication of which is causing which, but no sign at all of that 90 percent “threshold.”
       
In response, Ms. Reinhart and Mr. Rogoff have acknowledged the coding error, defended their other decisions and claimed that they never asserted that debt necessarily causes slow growth. That’s a bit disingenuous because they repeatedly insinuated that proposition even if they avoided saying it outright. But, in any case, what really matters isn’t what they meant to say, it’s how their work was read: Austerity enthusiasts trumpeted that supposed 90 percent tipping point as a proven fact and a reason to slash government spending even in the face of mass unemployment.
       
So the Reinhart-Rogoff fiasco needs to be seen in the broader context of austerity mania: the obviously intense desire of policy makers, politicians and pundits across the Western world to turn their backs on the unemployed and instead use the economic crisis as an excuse to slash social programs.
       
What the Reinhart-Rogoff affair shows is the extent to which austerity has been sold on false pretenses. For three years, the turn to austerity has been presented not as a choice but as a necessity. Economic research, austerity advocates insisted, showed that terrible things happen once debt exceeds 90 percent of G.D.P. But “economic research” showed no such thing; a couple of economists made that assertion, while many others disagreed. Policy makers abandoned the unemployed and turned to austerity because they wanted to, not because they had to.
       
So will toppling Reinhart-Rogoff from its pedestal change anything? I’d like to think so. But I predict that the usual suspects will just find another dubious piece of economic analysis to canonize, and the depression will go on and on.
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NDCDP-Économie générale.-
Liens vers les articles de Reinhart et Rogoff et de Herndon, Ash et Pollin:
  1. Reinhart-Rogoff:"Growth in a time of debt", NBER Working Paper, 26 pages, January 2010.[The views expressed are those of the authors and do not necessarily reflect the views of the NBER.] 
  2. Reinhart-Rogoff Initial Response, by Robin Harding, Financial Time, April 16, 2013
     

samedi 4 juillet 2009

Mesure de la croissance économique d'un pays

Le concept de croissance économique est l'un des plus importants de la théorie économique moderne. Il s'agit d'un concept global qui se mesure essentiellement à partir des grands agrégats de la comptabilité nationale.

La mesure de la croissance économique soit à partir du produit national brut (PIB), soit à partir du revenu national. Pour ce faire, on calcule le taux de variation de l'agrégat à chaque période par rapport à la période précédente.

On distingue la croissance en valeur de la croissance en volume.
La croissance en valeur est évaluée à prix courants, tandis que la croissance en volume est mesurée à prix constants.

Exprimons, pour les fins du raisonnement, la valeur du PIB d'un pays au cours d'une année donnée par l'équation suivante:

PIB = P x Q .......... (1)

Dans cette équation:
  • Q représente la quantité de biens produits au cours de l'année, hormis ceux de consommation intermédiaire;
  • P est le prix moyen de ces biens ou le niveau général des prix.
Supposons que le PIB s'accroît de delta_PIB par rapport à l'année précédente par suite d'une variation des prix, delta_P, et, d'un accroissement de la quantité de biens, delta_Q.

En se basant sur la notion de différentielle totale d'une fonction de deux variables, on peut écrire l'approximation suivante entre l'accroissement du PIB, la variation de P et l'accroissement de Q:

delta_PIB = P x (delta_Q) + Q x (delta_P) .......... (2)

Dans l'équation (2):

  • delta_PIB est la croissance en valeur ou à prix courants;
  • P x delta_Q est la croissance en volume ou à prix constants. Elle est due à l'accroissement de la quantité de biens produits seulement;
  • Q x delta_P est la croissance nominale due à la variation des prix seulement.

En divisant l'équation (2) par l'équation (1), membre à membre, on obtient, après simplification:

(delta_PIB) / PIB = (delta_Q)/ Q + (delta_P) / P .......... (3)

L'équation (3) montre que le taux de croissance en valeur, (delta_PIB)/PIB est égale à la somme du taux de croissance en volume, (delta_Q)/Q et du taux de variation du niveau général des prix, (delta_P)/P.

Les analyses de croissance concernent surtout le taux de croissance en volume, (delta_Q)/Q.

Si la variation de prix est nulle, le taux de croissance en valeur est égal au taux de croissance en volume.

Si la croissance en volume est nulle, le taux de croissance en valeur est égal au taux de variation du niveau général des prix.

En général, (delta_P)/P n'est pas nul. Alors, pour avoir le taux de croissance en volume, on l'isole à partir de l'équation (3):

(delta_Q)/Q = (delta_PIB) / PIB - (delta_P) / P .......... (4)

Le premier terme du second membre de (4), c'est-à-dire, le taux de croissance en valeur, est tiré directement des statistiques de la comptabilité nationale établies à prix courants. Le second terme du second membre de (4) est le taux de variation d'un indice du niveau général des prix.

Remarque.-

L'expression fournie dans l'équation (1) est le PIB nominal pour une période donnée. Pour avoir le PIB réel, on prend l'habitude de diviser le PIB nominal par le niveau des prix:

PIB réel = PIB nominal / niveau des prix .......... (5)

Mais, cette façon de procéder peut poser un problème quand les prix relatifs changent fortement. Le Bureau of Economic Analysis (BEA) américain, pour corriger un peu ce problème, fournit une mesure appelée: "PIB réel avec chaînage des pondérations". Par exemple, si l'on utilise les prix de 1996 comme base et ainsi, le PIB sera mesuré en dollars 1996 chaînés. Si par contre on utilise les prix de 2000 comme base, alors le PIB sera mesuré en dollars 2000 chaînés.

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Dans la préparation de cet article nous avons consulté, entre autres documents:

  1. Stiglitz, J. E. et Walsh, C. E. (2004) "Principes d'économie moderne", 2e édition, De Boeck et Larcier, 982 pages.
  2. Poulon, F. (2008) "Économie générale", 6e édition, Dunod, 336 pages.
  3. BEA: http://www.bea.gov/national/nipaweb/Index.asp
  4. http://en.wikipedia.org/wiki/Gross_domestic_product
  5. http://fr.wikipedia.org/wiki/Produit_int%C3%A9rieur_brut

dimanche 26 avril 2009

Haïti/ Les comptes économiques en 2008 - Hausse légère du PIB

Source: IHSI


L’exercice fiscal 2007-2008 aura été l’une des périodes les plus difficiles de l’économie haïtienne au cours de ces cinq dernières années. Affecté par de multiples chocs externes et internes, le Produit Intérieur Brut (PIB), selon les estimations préliminaires, n’a crû, en volume, que de 1.3% en 2008. En effet, les crises pétrolière et alimentaire, sur le plan mondial, et le passage successif des quatre ouragans, sur le plan interne, ont handicapé à des degrés divers l’évolution positive des différents secteurs de l’économie.

Cliques sur le lien suivant pour les détails:

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http://www.ihsi.ht/pdf/comptes_economiques_en_%202008.pdf
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