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<a accesskey="3" href="page.php?w=natural_experiment&amp;p=2">3.Next</a>
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<p>A <b>natural experiment</b> is a study in which individuals are exposed to <a href="page.php?w=experiment">experiment</a>al and <a href="page.php?w=scientific_control">control</a> conditions that are determined by <a href="page.php?w=nature">nature</a> or by other factors outside the control of the investigators. The exposure process may resemble <a href="page.php?w=random_assignment">random assignment</a>. Thus, natural experiments are <a href="page.php?w=observational_studies">observational studies</a> and are not <a href="page.php?w=scientific_control">controlled</a></p><p>
<a accesskey="3" href="page.php?w=natural_experiment&amp;p=2">3.Next</a>
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