Increasing work incentives for people with low incomes is a common topic in the policy debate across European countries. The Mini-Jobʺ reform in Germany - introduced on April 1, 2003 - can be seen in line with these policies, exempting labour income below a certain threshold from taxes and...

Many commonly used treatment effects estimators rely on the unconfoundedness assumption ("selection on observables") which is fundamentally non-testable. When evaluating the effects of labor market policies, researchers need to observe variables that affect both treatment participation and labor...