You can do either an experiment, where everything except the particular thing being tested is carefully controlled, or field work, where you study your subject in the natural world.
Manufacturers of products that claim to be environmentally friendly will face tighter rules on how they are advertised to consumers under changes proposed by the Federal Trade Commission.
When storing Renaissance oil paintings, museums conform to standards that call for careful control of the surrounding temperature and humidity, with variations confined within narrow margins.
A government study recommended a national highway system of 33,920 miles, and Congress passed the Federal-Aid Highway Act of 1944, which called for strict, centrally controlled design criteria.
The clinical literature on antidepressant drugs is massive, since large-scale, rigorous studies are required for market approval from the Food and Drug Administration (FDA).
Schools acknowledge the rigor of European secondary training, and will give up to a year's credit to foreigners who have passed their high school exams.