A natural experiment is an empirical study in which the experimental conditions (i.e., which units receive which treatment) are determined by nature or by other factors out of the control of the experimenters and yet the treatment assignment process is arguably exogenous. Thus, natural experiments are observational studies and are not controlled in the traditional sense of a randomized experiment. Natural experiments are most useful when there has been a clearly defined and large change in the treatment (or exposure) to a clearly defined subpopulation (and no change to a comparable subpopulation), so that changes in responses may be plausibly attributed to the change in treatments (or exposure).
Natural experiments are considered for study designs whenever controlled experimentation is difficult, such as in many problems in epidemiology and economics.
Read more about Natural Experiment: History
Famous quotes containing the words natural and/or experiment:
“Yet I experienced sometimes that the most sweet and tender, the most innocent and encouraging society may be found in any natural object, even for the poor misanthrope and most melancholy man. There can be no very black melancholy to him who lives in the midst of nature and has his senses still.”
—Henry David Thoreau (1817–1862)
“That which we call sin in others, is experiment for us.”
—Ralph Waldo Emerson (1803–1882)