It is therefore by definition always correct

Is that really worth the euro Returning from 1.60 dollar to slightly more than 1.20 dollar in less than two years, he almost lost a quarter of its value against the greenback. And it seems sometimes become the currency of the devil. He burned the hands of those who have and who RID by before whole cars sometimes the buy back the next day. It also burns the heads of experts, which announce a morning that everything is in place for a great rebound for the European currency before explaining the night she could well plunge. At the same time, this uncontrolled fall is also good news. Not only because, by stimulating exports, it restores air economy European still swamped by the consequences of the financial crisis of 2008, but also because it brings back the euro to a value considered as normal. It is the sense that reflected Wednesday John Lipsky, the number two of the international monetary fund: "the euro is rather close to what we regard as its equilibrium value after a long period where he traded over its value."

This is of course the market sets the value of currencies. It is therefore by definition always correct. But he also often anything - a less debatable fact, particularly on financial assets. As for the shares, economists are trying to determine the "fundamental" value of the currencies. The first technique is to look at purchasing power. The London weekly "the economist" and regularly compares Big Mac prices. In his last delivery in March, hamburger was on average 3.58 $ 3,36 euros and United States in the euro area. The exchange rate that would give the two currencies the same ability to purchase (experts speak of PPP, purchasing power parities) would thus 1 dollar to 1.07.

But, fortunately, we do eat not only Big Mac in life. Experts compare therefore only prices for sandwiches, but also those of the laundry, cars, telephone and all packages which is the food basket to calculate app sales. For 2009, the OECD provides a rate of 1.17 dollar for 1 euro and IMF 1.19 dollar. Just below the recent values - and by chance at the level of the first rating of the euro on January 4, 1999, at 1.18 dollar. Hence this feeling of "return to balance."

But this is not so simple. With a different calculation technique, the World Bank gives to the France in 2008 a slightly higher rate of 1.34 dollar. And the value of the currency explains not only - or even not at all - by the concern to give the same price to the carriage of the consumer in all countries. It is played on financial markets, supply and demand. Hamid Faruqee and Ronald MacDonald (not the Hamburger) economists have developed a technique of behavioural equilibrium exchange rates (Beer in English). She especially takes into account the possibility for a country to pay the interest to the rest of the world with its balance of trade surplus. According the calculations of the center of prospective studies and international information (Cepii) in 2008, the rate Beer would be around 1 euro to 1.10 dollar. Here, too, a bit below the current level.

The researchers of Cepii, Agnès Bénassy-Quéré, Sophie Béreau and Valérie Mignon, used another technique, the exchange rate of fundamental equilibrium (Feer in English) set by John Williamson - not to be confused with Oliver, the 2009 Nobel. It is to determine the exchange rate consistent with a "sustainable" current-account deficit set at 3 of GDP in the United States. It leads to significantly different figures: the rate should be then around 1.50 dollar for 1 euro, or even more than 2 dollars in certain extreme cases!

However, these models have a bias which today becomes a weakness. They are based on external imbalances, which are mostly Americans. For the year 2010 for example, the IMF forecasts a deficit of US $ 500 billion current-account while the euro area would be at equilibrium. If this deficit is still huge, the financial crisis did return in the famous area of 3 of GDP found bearable, because Americans less spent and more exported. The main problem today is Europe (to the day where investors rediscovered the appalling situation of the US account, both Treasury and the Federal Reserve).

The slide of the euro is perhaps a simple response to deep anxiety: European growth will be too low to pay off heavy debts. If it refuses to default, inflation or the spread of the debt, only room for manoeuvre left to the old Continent is the devaluation of its currency. Patrick Artus, Chief of Natixis Economist, sales necessary down to 30, which boost European growth of 1.5 per year. The figure appears of course enormous. It would reduce the euro below the 90 cents, as in 2000. But after all, the United Kingdom is out of the great depression in devaluing the pound from 40 a coup in 1931.