Natural Experiments and Quasi-Natural Experiments

The term ‘natural experiment’ has been used in many, often, contradictory, ways. It is not unfair to say that the term is frequently employed to describe situations that are neither ‘natural’ nor ‘experiments’ or situations which are ‘natural, but not experiments’ or vice versa. These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.