This paper investigates whether the inherent non-stationarity of macroeconomic time series is entirely due to a random walk or also to non-linear components. Applying the numerical tools of the analysis of dynamical systems to long time series for the US, we reject the hypothesis that these series are generated solely by a linear stochastic process. Contrary to the Real Business Cycle theory that attributes the irregular behavior of the system to exogenous random factors, we maintain that the fluctuations in the time series we examined cannot be explained only by means of external shocks plugged into linear autoregressive models. A dynamical and non-linear explanation may be useful for the double aim of describing and forecasting more accurately the evolution of the system. Linear growth models that find empirical verification on linear econometric analysis, are therefore seriously called in question. Conversely non-linear dynamical models may enable us to achieve a more complete information about economic phenomena from the same data sets used in the empirical analysis which are in support of Real Business Cycle Theory. We conclude that Real Business Cycle theory and more in general the unit root autoregressive models are an inadequate device for a satisfactory understanding of economic time series. A theoretical approach grounded on non-linear metric methods, may however allow to identify non-linear structures that endogenously generate fluctuations in macroeconomic time series. (authors' abstract) / Series: Working Papers Series "Growth and Employment in Europe: Sustainability and Competitiveness"

Thesis advisor: Peter Ireland / Thesis advisor: Matteo Iacoviello / The dissertation is composed by two chapters. In the first one, I study the role of credit constraints and incomplete markets in the short run transmission of monetary shocks, using the superneutrality result that would obtain from preference separability in the Sidrauski model under complete markets as a benchmark. I find that money demand heterogeneity stemming from binding credit constraints invalidates the superneutrality result. I show this result under two alternative settings. In a simple two agents model, with heterogeneity in the rates of time preference, whether positive shocks to the growth rate of money are expansionary or contractionary crucially depends on the transfer scheme adopted by the monetary authority to rebate seigniorage transfers: redistributional effects implied by symmetric lump-sum transfers are contractionary, while wealth-neutral transfers are expansionary. In a model with uninsurable idiosyncratic risk, the approximate aggregation property fails to hold due to the high degree of heterogeneity of money demand and to the properties of the cross-sectional distribution of money holdings, suggesting the inadequacy of the representative agent assumption and the need for a more elaborate approximation of the wealth distribution to predict prices. In the second chapter, we propose a real business cycle model with labor and credit market frictions in which borrowing is conditional on employment status. Relative to a conventional set up, and as long as credit is valued positively, our model generates a non-standard labor/leisure trade off that induces job applicants to accept lower wages and firms to post more vacancies, ultimately increasing employment. A shock to the demand of durable goods, by increasing the collateral value, reduce the opportunity cost of working, and generates an increase in employment and output. The transmission of a financial shock that increases the loan to value ratio, is dampened by the costs, in terms of leisure, incurred by the borrowers. We show that this mechanism is able to generate the positive comovement between outstanding household debt and employment observed in the data, whereas a conventional model, in which employment status is irrelevant for obtaining credit, predicts a counterfactual negative comovement. / Thesis (PhD) — Boston College, 2012. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Economics.

Presented here are consumption and production related asset pricing models which seek to explain stock market behaviour through the stock premium over risk-free bonds and to do so using parameter values consistent with theory. Our results show that there are models capable of explaining stock market behaviour. For the consumption-based model, we avoid many of the suggestions to artificially boost the predicted stock premium such as modelling consumption as leverage claims; instead we use the notion of surplus consumption. We find that with surplus consumption, there are models including the much-maligned power utility model, capable of yielding theory consistent estimates for the discount rate, risk-free rate as well as the coefficient of relative risk aversion, y. Since real business cycle theory assumes a risk aversion coefficient of 1, we conclude that our model which gives a value close to but not equal to 1, provides an indication of the impact of market imperfections. For production, we present many of the existing models which seek to explain stock market behaviour using production data which we find to be generally incapable of explaining stock market behaviour. We conclude by presenting a profit based formulation which uses deviations of actual from expected profits and dividends via stock price reaction parameters to successfully explain stock market behaviour. We also conclude that the use of a profit based formulation allows for a link to investment, output and pricing decisions and hence link consumption and production.