The concept of managed competition in health care attracts a lot of attention from policy makers not only in Germany but from countries all around the world. The aim of this concept is to increase the efficiency of health care systems as well as maintaining solidarity. Since the health care...

The evaluation of interventions such as active labor market policies or medical programs by means of a randomized controlled trial is often considered the gold standard. However, randomized experiments might face severe shortcomings especially if performed at the group level. One such problem is...