and actual variables consumption investment etc

Here are more than thirty years that fluctuations in activity have become truly global. The collapse of "bubble" caused by an excessive growth of asset prices (shares and real estate including) plays a role more important; He is originally of three recent shaking that we have seen, although unequal importance, but all international dimension: bursting of a housing bubble in the early 1990, ICT bubble in the early 2000s and break-up of a new bubble from the summer 2007.

Central banks are again, here or there, fighting a rearguard action with regard to the control of these asset prices. The first argument put forward is that it does not explicitly appear in their mission. They must be mainly contain inflation, i.e. the General increase in the price of goods produced in the year. Many assets do not correspond to this definition; but it is clear that must be addressed here another definition of the price control exercised by the central banks. The monitoring of the evolution of the price of the common property "auto-équilibrants", must be added that of price changes on the "auto-déséquilibrants" markets that are the markets for financial assets or financial.

A second argument for not directly control the prices of assets was that, by monitoring of inflation in the traditional sense, it identified in reality all the imbalances associated with asset price developments: in fact, when they correspond to major increases, are at the origin of wealth effects that expand the application and are therefore likely to appear in the usual sense of the inflationary. Unfortunately, the episodes in which he was made reference above have sufficiently shown that increases in prices of consumer goods were one thing and that of asset prices was another, quite different in its manifestations as in its causes.

Either, but then, last argument: assume that he must truly control the evolution of asset prices, but who can say with certainty that any increase in the price of a given asset is overstated and does not really match the "basic" price changes in scarcity-related This last argument comes himself from falling.

Researchers from the European Central Bank have indeed, for 18 countries of the OECD, recently identified indicators to predict, with a very high probability, the bursting of an asset price bubble sufficiently in advance to ensure that interventions are possible (1). They thus tested 89 indicators involving financial variables (interest rates at three months, bank loans, etc.) and actual variables (consumption, investment, etc.). A experience, one of them is clear: the amount of bank credit to the private sector. When the amount of these credits crosses a threshold which strongly away it from its trend, there are more than eighty chances on hundred for that this "signal" announced, during the six quarters following the bursting of an asset price bubble, burst generator of a fall in growth "at cost", as the say researchers. Of course, cannot deal with such indicators lightly and we have much simplified the precautions taken by them to go as low as possible the risk of detecting a bubble burst, while nothing will really happen.

It should also be thinking about the behavior of the Central Bank if an indicator of this type began to emit a signal of likely collapse of bubble over the next six quarters: dissemination of information in the direction of officers and non-financial particularly concerned constitutes a first initiative which can have its effectiveness; This course will depend on the "credibility" of the flag used by the Bank. But it may also decide to make use of the instruments in his possession to "fight against the wind". Recent events showed that monetary policy (interest rates increase) was of course one of them, but that there were also several others.

It is quite certain that we are beginning the research of leading indicators of asset price bubble burst. Can certainly think of others, only involving the actual variables (for example, for households, the heritage-income report) or combining financial and real variables (for example, the liabilities-income report). It is clear that referring not only to an indicator but several at the same time, it will increase the chances of relevant interventions. This research relates logically to the implementation of this macro-financial monitoring which are perceived well that our capitalism can no longer, in the future happen.