a natural experiment
) to credibly estimate the causal effect of some
In the literature the common view is a trade-off between internal and external validities, and natural experiments
lie in the middle of the scale (16).
From geology and evolutionary biology, the idea has migrated into the social sciences, which are the focus of Diamond and Robinson's Natural Experiments
In the second natural experiment
, the City University of New York (CUNY) in 1970 went from having a highly selective admissions process to open enrollments almost overnight.
(5) El-Gamal and Sundaram (1993) highlight the importance of natural experiments
In a meta-analysis limited to five randomised controlled trials and one natural experiment
, it is concluded that custodial and non-custodial sanctions do not differ significantly in terms of re-offending.
Product usability testing can be conceptualized as quasi and natural experiments
. In product usability testing, researchers assess user performance on products.
We considered 2 subgroups of eligible studies separately: the RCTs and CCTs or natural experiments
that had nonherbal/ Ayurvedic comparison arm(s) were considered 1 subgroup, and all other eligible (pre/post data available) studies made up the second subgroup.
Three approaches to ecological research were used in this study: observation, natural experiments
, and field manipulation experiments (sensu Diamond 1986).
Much of the literature which looks at the welfare magnet hypothesis has dealt with contemporary "natural experiments
" as essentially miniature laboratories to see how poor individuals react to relatively minor policy changes.(3) Never has anyone studied historical welfare, known at the time as poor relief, to see if there were such tendencies for migration when adjoining jurisdictions offered relatively more attractive benefits.(3) In this paper, our goal is to test if a historical welfare magnet existed in the United States during the nineteenth century.
We don't take advantage of the natural experiments
our federal system generates when states take the initiatives to experiment with new programs.
The book's new empirical evidence on the employment effects of a minimum wage hike is from seven "natural experiments
." These find the proportional change in employment after and before a minimum wage hike for each unit of observation, (employer or state), and compare these changes for units with different "exposures" to the hike.
(11.) In the social sciences, researchers conduct "natural experiments
" by seeking out and comparing situations in which the factors under study vary while other conditions remain constant.
Because minimum wage changes occur in discrete exogenous jumps over time and across areas, they constitute "natural experiments
." Card and Krueger exploit this variation admirably.
Identical twins growing up in different families have long been seen as "natural experiments
" in human genetics, even by the eugenicists of the 1920s.