Bennett, M.D., M.P.H., from the Johns Hopkins University School of Medicine in Baltimore, and colleagues conducted a systematic review of 194 natural experiments
and experimental studies assessing a program, policy, or built environment change by using measures of obesity or obesity-related health behaviors.
There is a way to make natural experiments
satisfy the condition for random experiments.
The role of trade and investment liberalization in the sugar-sweetened carbonated beverages market: a natural experiment
contrasting Vietnam and the Philippines.
(6) However, a previous natural experiment
, which used data from the closure of a large Utah Valley steel mill between August 1986 and September 1987, did not find a difference in birth weights between babies born before, during, or after the closure.
that credible natural experiments
are inherently limited in scope.
Treating variation in the amount of time that states mandate schoolchildren spend in PE as natural experiments
, the researchers found that an additional 60 minutes per week of PE time (enough to bring states without an explicit requirement up to the amount of PE recommended by the CDC) reduces the probability that a fifth-grader is obese by 4.8 percentage points.
Difference-in-differences (DID) strategies are particularly useful for evaluating policy effects in natural experiments
in which, for example, a policy affects some schools and students but not others.
, which compare two countries with similar social, economic, cultural, and religious characteristics--but with differing approaches to family planning programs--also demonstrate the powerful impact of voluntary family planning.
Economists and political scientists describe recent developments in studying corruption based on laboratory, field, and natural experiments
. Corruption has two essential elements, they say: a public official breaking rules for private gain, and secrecy.
are in fashion in Social Sciences.
Research by Professor Simon Capewell and Dr Martin O'Flaherty at the Institute of Psychology, Health and Well-being, looked at evidence from clinical trials and natural experiments
. They found that a reduction in smoking has a positive impact on mortality rates in both individuals and populations within six months.