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Endogenous risk and long run effects of liberalisation in a global analysis framework

Boussard J.M., Gérard F., Piketty M.G., Ayouz M., Voituriez T.. 2004. In : Trade, Poverty, and the Environment. Seventh Annual Conference on Global Economic Analysis, Washington, USA, 17-19 June 2004. Nogent-sur-Marne : Cirad-Amis, 25 p.. Annual Conference on Global Economic Analysis. 7, 2004-06-17/2004-06-19, Washington (Etats-Unis).

In a classical Walrassian framework of smoothly functioning markets and comparative static analysis, the beneficial effects of trade liberalisation are well known. In the real world, production decisions develop along time. They are fringed with uncertainty, and subject to unfulfilled expectations. Depending upon demand elasticity, such phenomena lead to converging or diverging cobwebs. Yet, even if demand is inelastic, diverging cobwebs are rarely observed, because there exist also many return strings which call systems back in the vicinity of (unstable) equilibrium. Among the latter, as already noticed by Knut Wicksell in the 1930's, attitudes toward risk and investment functions play a large role. In effect, introducing such mechanisms into a dynamic market equilibrium leads to "chaotic motion", a now well documented mathematical being, with very specific characteristics. In this context, market price fluctuations no longer occur because of the "hand of God", from completely external sources, such as climatic events. They are endogenous, generated by the market itself. While external risk is subject to the "law of large number", thus allowing for the benefit of risk pooling through insurance mechanisms, endogenous is not. In particular, any effort to lower individual decision maker exposition to risk affects the values of the key model parameters, such as supply elasticity, thus changing the risk regime itself. Now, while many studies (especially by Hertel et al) have been undertaken in order to elicit the consequences of external risk for the magnitude and distribution of the trade liberalisation benefits, the endogenous risk case has generally been benignly ignored by the world research community. The present paper aims at filling this gap. To this end, a GTAP model along that line is developed, with and without agricultural liberalisation. It is shown that, after a while, the tendency to divergence is smoothed out by risk considerations. Yet, because of a grea

Mots-clés : libéralisation des échanges; marché des produits de base; commerce international; fixation des prix; risque; modèle mathématique; offre et demande; technique de prévision

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