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:
“I’ve always been impressed by the different paths babies take in their physical development on the way to walking. It’s rare to see a behavior that starts out with such wide natural variation, yet becomes so uniform after only a few months.”
—Lawrence Kutner (20th century)
“To me the sole hope of human salvation lies in teaching Man to regard himself as an experiment in the realization of God, to regard his hands as God’s hand, his brain as God’s brain, his purpose as God’s purpose. He must regard God as a helpless Longing, which longed him into existence by its desperate need for an executive organ.”
—George Bernard Shaw (1856–1950)