Does happiness vary with age? The evidence is inconclusive. Some studies show happiness to increase with age (Diener et al. 1999; Argyle 2001). Others hold that the association is U-shaped with either highest depression rates (Mroczek and Christian, 1998; Blanchflower and Oswald, 2008) or highest...

Borders have a sizable negative impact on trade flows. Given the vast number of individual goods potentially traded, this "border effect" could have two possible explanations: (1) less international than domestic trade in the goods that are actually traded between countries ("flow"), or (2)...