Essays on macroeconomic theory.

Summary This thesis is composed of three independent chapters. The first chapter concerns the formation of expectations. I show that agents are likely to use a misspecified model rather than the "true" model of the economy. I consider a simple economy with two types of agents. Rational agents learn the rational expectation solution while "consistent" agents use an autoregressive model. I show that a long-run equilibrium in which coherent agents are dominant exists. Simulations show that the economy can converge to this equilibrium. The second chapter concerns intertemporal choice. I consider a model in which wealth enters into utility. I study the non-separable case, separating the income effect on labor supply from the intertemporal substitution effect. I deduce implications for economic policy and then estimate the two parameters introduced by this specification of utility. I find positive and high values for both. The third chapter presents a model of investment in the presence of adverse selection. My contribution is to provide a simple solution, easy to integrate in a macroeconomic model. Borrowers differ by the risk of their investment project as in Stiglitz and Weiss (1981). They signal the risk of their project by borrowing a fraction of the profits set aside. I obtain an analytical solution for the incentive constraint. I integrate it into a dynamic model and derive some implications.