Geometry for a `penguin-albatross' rookery

We introduce a simple ecological model describing the spatial organization of two interacting populations whose individuals are indifferent to conspecifics and avoid the proximity to heterospecifics. At small population densities $\Phi$ a non-trivial structure is observed where clusters of individuals arrange into a rhomboidal bipartite network with an average degree of four. For $\Phi\rightarrow0$ the length scale, order parameter and susceptibility of the network exhibit power-law divergences compatible with hyper-scaling, suggesting the existence of a zero density - non-trivial - critical point. At larger densities a critical threshold $\Phi_{c}$ is identified above which the evolution toward a partially ordered configuration is prevented and the system becomes jammed in a fully mixed state

Economic and Political Liberalizations

This paper studies empirically the effects of and the interactions amongst economic and political liberalizations. Economic liberalizations are measured by a widely used indicator that captures the scope of the market in the economy, and in particular of policies towards freer international trade (cf. Sachs and Werner 1995, Wacziarg and Welch 2003). Political liberalizations correspond to the event of becoming a democracy. Using a difference-in-difference estimation, we ask what are the effects of liberalizations on economic performance, on macroeconomic policy and on structural policies. The main results concern the quantitative relevance of the feedback and interaction effects between the two kinds of reforms. First, we find positive feedback effects between economic and political reforms. The timing of events indicates that causality is more likely to run from political to economic liberalizations, rather than viceversa, but we cannot rule out feedback effects in both directions. Second, the sequence of reforms matters. Countries that first liberalize and then become democracies do much better than countries that pursue the opposite sequence, in almost all dimensions.political liberalization, democracy, economic reform.

The Household Effects of Government Spending

This paper provides new evidence on the effects of fiscal policy by studying, using household-level data, how households respond to shifts in government spending. Our identification strategy allows us to control for time-specific aggregate effects, such as the stance of monetary policy or the U.S.-wide business cycle. However, it potentially prevents us from estimating the wealth effects associated with a shift in spending. We find significant heterogeneity in households' response to a spending shock; the effects appear vary over time depending, among other factors, on the state of business cycle and, at a lower frequency, on the composition of employment (such as the share of workers in part-time jobs). Shifts in spending could also have important distributional effects that are lost when estimating an aggregate multiplier. Heads of households working relatively few (weekly) hours, for instance, suffer from a spending shock of the type we analyzed: their consumption falls, their hours increase and their real wages fall.Fiscal policy, PSID, household consumption, labor supply

The Household Effects of Government Spending

This paper provides new evidence on the effects of scal policy by studying, using household-level data, how households respond to shifts in government spending. Our identi cation strategy allows us to control for time-specific aggregate effects, such as the stance of monetary policy or the U.S.-wide business cycle. However, it potentially prevents us from estimating the wealth e ects associated with a shift in spending. We find significant heterogeneity in households' response to a spending shock ; the effects appear vary over time depending, among other factors, on the state of business cycle and, at a lower frequency, on the composition of employment (such as the share of workers in part-time jobs). Shifts in spending could also have important distributional effects that are lost when estimating an aggregate multiplier. Heads of households working relatively few (weekly) hours, for instance, suffer from a spending shock of the type we analyzed : their consumption falls, their hours increase and their real wages fall. Key words: Fiscal Policy ; PSID ; Household Consumption ; Labor Supply JEL classification: E62 ; E21 ; E24 ; D12

Can Severe Fiscal Contractions be Expansionary? Tales of Two Small European Countries

According to conventional wisdom, a fiscal consolidation is likely to contract real aggregate demand. It has often been argued, however, that this conclusion is misleading as it neglects the role of expectations of future policy: if the fiscal consolidation is read by the private sector as a signal that the share of government spending in GDP is being permanently reduced, households will revise upwards their estimate of their permanent income, and will raise current and planned consumption. Only the empirical evidence can sort out which of these two contending views about fiscal policy is more appropriate -- i.e how often the contractionary effect of a fiscal consolidation prevails on its expansionary expectational effect. This paper brings new evidence to bear on this issue drawing on the European exercise in fiscal rectitude of the 1980s, and focusing, in particulars on its two most extreme cases -- Denmark and Ireland. We find that at least in the experience of these two countries the expectations' view has a serious claim to empirical relevance.