Difference-in differences strategies are simple panel data methods applied to sets of group means in cases when certain groups are exposed to the causing variable of interest and others are not. The approach is well suited to estimating the effect of sharp changes in the economic environment or changes in government policy when a suitable control group can be found. We’ll consider the Diff-indi...

Lewbel (2012) provides an estimator for linear regression models containing an endogenous regressor, when no outside instruments or other such information is available. The method works by exploiting model heteroscedasticity to construct instruments using the available regressors. Some authors have considered the method in empirical applications where an endogenous regressor is binary (e.g., en...

This paper makes use of the revision of “Law on the Prevention and Control of Water Pollution” as a natural phenomenon, under the method of Difference-in-Differences to observe the effect of this policy on the reduction of industrial wastewater in Beijing-Tianjin-Hebei region. The research result shows that the implementation of the policy has certain promoting effect to reduce discharge of ind...

In 2000 Italy replaced its traditional system of severance pay for public employees with a new system. Under the old regime, severance pay was proportional to the final salary before retirement; under the new regime it is proportional to lifetime earnings. This reform entails substantial losses for future generations of public employees, in the range of €20,000-30,000, depending on seniority. U...

This paper investigates how the European integration process of central eastern European countries, which has been taking place since the 1990’s, affects their GDP growth. Based on an augmented Solow model, I estimate a convergence equation for a panel of ten countries over 16 years (19952010). In the regression, trade with the other European Union member states as a share of total trade serves...

This paper examines the effects of the Medicaid expansions of the late 1990s on the insurance coverage of poor adolescents. To control for the potentially confounding influences of competing trends, I use a difference-in-differences strategy that employs a comparison group of poor younger children who gained public insurance eligibility several years prior to their older peers. Results suggest ...

I provide new evidence on the relative “powers” of contraception and abortion policy in effecting the dramatic social transformations of the 1960s and 1970s. Trends in sexual behavior suggest that young women’s increased access to the birth control pill fueled the sexual revolution, but neither these trends nor difference-in-difference estimates support the view that this also led to substantia...

This paper studies the effect of product market competition on the explicit compensation packages that firms offer to their CEOs, executives and workers. We use a large sample of both traded and non-traded UK firms and exploit a quasi-natural experiment associated to an increase in competition. The sudden appreciation of the pound in 1996 implied different changes in competition for sectors wit...

We exploit the 1983 language-in-education reform that introduced Catalan alongside Spanish as medium of instruction in Catalan schools to estimate the labour market value of bilingual education. Identification is achieved in a difference-in-differences framework exploiting variation in exposure to the reform across years of schooling and years of birth. We find positive wage returns to bilingua...

A randomised controlled trial was conducted to determine changes in the food and drink choices of adolescents following their participation in a one-day nutrition workshop. The experiment was conducted at 104 schools in Barcelona (126 classes, 3,291 adolescents). Schools were randomly delected stratifiying by district and by public/private. The students were given three kinds of vouchers, with ...