Suchergebnisse

Conventional difference-in-differences (DID) methods that are used to estimate the effect of a treatment rely on important identifying assumptions. Identification of the treatment effect in a DID framework requires some assumption relating trends for controls and treated in absence of treatment, the most common being the assumption of Parallel Paths. When several pre-treatment periods are available, Mora and Reggio (2012) show that treatment effect identification does not uniquely depend on the Parallel Path assumption, but also on the trend modeling strategy. They further define a family of alternative Parallel assumptions and propose a more flexible model which can be a helpful starting tool to study robustness to alternative Parallel assumptions and trend dynamics. In this paper we introduce a Stata command that implements the fully flexible model presented in Mora and Reggio (2012), producing tests for the equivalence of alternative parallel assumptions and for the dynamic effects of the treatment. The standard DID in model with or without polynomial trends can also be obtained. ; We acknowledge financial help from the Spanish government through grant ECO2012-31358.

The core assumption to identify the treatment effect in difference-in-differences estimators is the so-called Parallel Paths assumption, namely that the average change in outcome for the treated in the absence of treatment equals the average change in outcome for the non-treated. We define a family of alternative Parallel assumptions and show for a number of frequently used empirical specifications which parameters of the model identify the treatment effect under the alternative Parallel assumptions. We further propose a fully flexible model which has two desirable features not present in the usual econometric specifications implemented in applied research. First, it allows for flexible dynamics and for testing restrictions on these dynamics. Second, it does not impose equivalence between alternative Parallel assumptions. We illustrate the usefulness of our approach by revising the results of several recent papers in which the difference-in-differences technique has been applied.The core assumption to identify the treatment effect in difference-in-differences estimators is the so-called Parallel Paths assumption, namely that the average change in outcome for the treated in the absence of treatment equals the average change in outcome for the non-treated. We define a family of alternative Parallel assumptions and show for a number of frequently used empirical specifications which parameters of the model identify the treatment effect under the alternative Parallel assumptions. We further propose a fully flexible model which has two desirable features not present in the usual econometric specifications implemented in applied research. First, it allows for flexible dynamics and for testing restrictions on these dynamics. Second, it does not impose equivalence between alternative Parallel assumptions. We illustrate the usefulness of our approach by revising the results of several recent papers in which the difference-in-differences technique has been applied ; Both authors acknowledge financial help from the Spanish government through grant ECO2012-31358

AbstractBetween the 1940s and 1970s, Spain used a variety of economic policies that hindered international trade. Because the mix of tariffs, quotas, administrative barriers, and exchange rate regimes varied greatly over time, the quantification of the effect of the various trade policies on international trade in this period is particularly elusive. In this paper, we use historical bilateral trade flows and a structural gravity model to quantify the evolution of Spain's border thickness, a summary measure of its barriers to international trade. We find that Spain's borders in the period 1948–75 were thicker than those of any other country in Western Europe, even after the liberalization of trade that started in 1959. These comparatively higher impediments to international trade implied substantial negative effects on consumer welfare. We estimate that accumulated welfare costs over the period 1948–75 exceed 20 per cent of a year's total consumption.

The literature has identified three main approaches to account for the way exchange rate regimes are chosen: i) the optimal currency area theory; ii) the financial view, which highlights the consequences of international financial integration; and iii) the political view, which stresses the use of exchange rate anchors as credibility enhancers in politically challenged economies. Using de facto and de jure regime classifications, we test the empirical relevance of these approaches separately and jointly. We find overall empirical support for all of them, although the incidence of financial and political aspects varies substantially between industrial and non-industrial economies. Furthermore, we find that the link between de facto regimes and their underlying fundamentals has been surprisingly stable over the years, suggesting that the global trends often highlighted in the literature can be traced back to the evolution of their natural determinants, and that actual policies have been little influenced by the frequent twist and turns in the exchange rate regime debate.

Abstract
We develop a novel way of identifying the liquidity and moral hazard effects of unemployment insurance exclusively from how job-finding rates respond to unemployment benefits that vary over an unemployment spell. We derive a sufficient statistics formula for the dynamically optimal level of unemployment benefits based on these two effects. Using a regression kink design (RKD) that simultaneously exploits two kinks in the schedule of unemployment benefits, we apply our method to Spain for the years 1992–2012 and find that moral hazard effects dominated liquidity effects, suggesting that Spanish unemployment benefits exceeded the optimal level in that period.