The transition from communism to capitalism at the end of the last century was one of the most significant events in the world economy since industrialization. During the latter part of the 1980s, people the Central and Eastern European countries and former Soviet Republics opted for a change from highly distorted command economic system to a market driven economic system. Privatization and liberalization policies led to major changes in the commodity mix and volume of agricultural production, consumption and trade. However, the changes and the impacts varied among countries as they followed different transition strategies. This study investigated the impact of market liberalization on the agricultural sector, as well as how the inter-sectoral linkages among the agricultural, industrial and service sectors responded in Poland, Romania, Bulgaria and Hungary using time-series analysis. The study estimated an econometric model that incorporates the linkages among the sectors using a Vector Error Correction Model. The procedure identified long-run and short-run relationships for each country. The results showed that a sector can have a negative linkage to other sectors in the short-run; however, that does not mean that the linkage will be negative in the long-run. Impulse response functions were constructed to determine how a system reacts to a shock in one of the endogenous variable in a model. The study explored how a shock in the agricultural sector was absorbed by the other sectors in the economy, and how a shock in the other sectors was absorbed by the agricultural sector, in all four countries. The responses reflected how the variables are interrelated within a country, and how the shocks are transferred through different linkages over a long period of time. Such dynamic analysis was used to identify the total impacts of different policy alternatives.

Dans une série d'essais empiriques, cette thèse analyse les effets de la diversification productive sur la volatilité et la productivité dans les pays riches en ressources naturelles. Dans le premier chapitre, je montre que bien que les ressources naturelles affectent négativement la croissance économique en augmentant la volatilité, les pays riches en ressources peuvent compenser les effets déclencheurs de la volatilité des ressources en diversifiant leurs économies. Les pays dont la structure de production est initialement plus diversifiée, ou qui parviennent à se diversifier au cours de leur développement économique, sont susceptibles de bénéficier de leur dotation en ressources. Dans le deuxième chapitre, j’explique que les pays riches en ressources disposés à diversifier leurs économies pour stimuler leur productivité sont confrontés à deux choix; soit développer des industries axées sur les ressources, soit diversifier leur économie dans son ensemble vers de nouvelles activités qui ne dépendent pas nécessairement des ressources naturelles. L’analyse empirique montre que la diversification par les liens vers l’aval du secteur de l'exploitation minière ne conduit pas à des améliorations de productivité. En revanche, l'élargissement et la diversification de la structure de production dans son ensemble offrent des potentiels de croissance de la productivité à des niveaux de revenus plus élevés. Dans le troisième chapitre, j’analyse la relation entre la diversification et la volatilité du point de vue du réseau de production constitué par l’ensemble des liens d’approvisionnement entre secteurs. Je trouve que l'emplacement d'un secteur au sein du réseau et son influence sur d'autres secteurs ont des effets contradictoires sur le risque que les fluctuations subies par ce secteur génèrent une volatilité agrégée. Les secteurs situés dans des régions denses du réseau ont un effet atténuant sur la volatilité globale via les effets de substitution, tandis que ceux qui sont plus influents et au centre d'un réseau fortement asymétrique génèrent des fluctuations globales via les effets de contagion et les liaisons intersectorielles. Ceux-ci suggèrent que la répartition et la structure des liens interindustriels jouent un rôle important dans la façon dont la diversification conditionne l'impact des chocs idiosyncrasiques sur la volatilité globale. / In a series of empirical essays, this thesis looks at the various intertwining aspects of growth volatility and productive diversification in resource-rich countries. In the first chapter, I find that while natural resources adversely affect economic growth by increasing growth volatility, resource-rich countries can offset the volatility-triggering effects of natural resources by diversifying their economies. Countries that start off with more diversified production structure or are able to diversify as they develop are likely to benefit from their resource endowment. In the second chapter, I discuss the fact that resource-rich countries willing to diversify their economies are faced with dual policy options; to either develop resource-based industries, or diversify their economies as a whole into new activities not necessarily dependent on natural resources. The empirical analysis shows that diversification through downstream and forward linkages to mining does not lead to productivity enhancements. However, broadening and diversifying the production structure as a whole offer potentials for productivity growth at higher levels of income. In the third chapter, I look at the relation between diversification and volatility from a production network perspective, composed of input-output linkages across sectors. I find that the location of a sector within the production network and its influence on other sectors have conflicting effects on the risk that sectoral shocks lead to aggregate volatility. Sectors that are located in dense parts of the network have a mitigating effect on aggregate volatility via substitution effects, while those that are more influential and central in a strongly asymmetrical network generate aggregate fluctuations via contagion effects and inter-industry linkages. These suggest that the distribution and the network structure of inter-industry linkages play an important role into how diversification conditions the impact of idiosyncratic shocks on aggregate volatility.