Book excerpt: This thesis explores two important aspects of growth, namely the roles of financial development and inequality. The recent literature has indicated that both the finance-growth and inequality-growth relationships are complex and not well captured through conventional linear regression analyses. Thus, most of the existing empirical literature focuses on marginal or direct growth effects, ignoring the role of possible factors, conditions and thresholds that may alter our thinking about how financial development or inequality may affect economic growth. Further, it ignores the presence of outliers, especially in cross-sectional analyses which may hinder our understanding of these relationships. Therefore, Chapter 1 addresses the issue of outliers in finance-growth literature and provides a robust sensitivity analysis of some past studies and an updated data set. Chapter 2 focuses on whether R&D plays a role, potentially as a proxy for an omitted variable, for growth and whether it has important interactions with financial development. Chapter 3 then examines the role of inequality for growth, allowing the effects to differ depending on the level of human versus physical capital accumulation. The cross-sectional analysis of Chapter 1 employs the robust regression methods of median quantile regression and least trimmed squares. It shows that the findings of past studies are sensitive to outlier observations. Further, we find that the positive effect of financial development on growth disappears and even becomes negative once we use our extended data set of 86 countries over the period 1997-2006. This last finding is consistent with Rousseau and Wachtel (2011). Moreover, we investigate whether our understanding of the finance-growth relationship can further be improved by introducing a measure of R&D into the standard analysis. We note that our measure of R&D has a strong positive effect on growth and may proxy the role of an omitted variable which is highly correlated with economic growth. Chapter 2 also uses R&D and investigates its interaction with conventionally measured financial development. It employs a variety of panel data techniques for a panel of 36 OECD and non-OECD countries to show that the relationship between financial development and economic growth is not straightforward; rather, it is conditional upon the level of innovation or R&D. Further, we find that a high level of technological innovation or R&D is associated with a weak or negative effect of financial development on economic growth. It is also noted that R&D is associated with financial innovation and the results suggest that countries with a high level of R&D may have less regulated financial systems which can adversely affect the finance-growth relationship. The third chapter explores the relationship between inequality and growth in the context of a unified empirical approach suggested by the theoretical model of Galor and Moav (2004). Based on that model, we construct a new measure, the human capital to physical capital ratio, which is used to study threshold effects in the inequality-growth relationship. Methodologically, we use threshold regression with instruments, developed by Caner and Hansen (2004), which allows us to endogenously identify the threshold human capital to physical capital ratio that alters the inequality-growth relationship. Using data on 82 countries, our results show that there exist significant threshold effects, with a level of the human capital to physical capital ratio below which the effect of inequality on growth is positive and significant, whereas it is negative and significant above it. We also test the robustness of our results using different measures of the human capital to physical capital ratio. These results are consistent with the theoretical predictions of Galor and Moav (2004).