Random assignment is intended to create comparable treatment and control groups, reducing the need for dubious statistical models. Nevertheless, researchers often use linear regression models to "adjust" for random treatment-control differences in baseline characteristics.
One of the frustrations facing job seekers worldwide, but especially in many developing countries, is how much finding a job depends on who you know rather than what you know. For example, in work I’ve done with small enterprises in Sri Lanka, less than 2 percent of employers openly advertised the position they last hired – with the most common ways of finding a worker being to ask friends, neighbors or family members for suggestions. Clearly networks matter for finding jobs.
In an interesting new paper, Jens Ludwig, Jeffrey Kling and Sendhil Mullainathan argue that economists should be doing more experiments to identify behavioral mechanisms, and that these can be central to policy, even if the experiments themselves are far from what a policymaker would implement. So what are these mechanism experiments, and what can we learn from them?