Random sampling allows you to make an estimate of the populations of different species in any area. It should eliminate sampling bias introduced by the sampler selecting areas that look interesting or easier to count.
How do medical researchers study the effect certain drugs have on the human body? They make sure to conduct what’s called a blind study . A blind study is one where the people being tested have no idea whether they’re taking the drug itself or a placebo— a pill or drink containing no drugs at all. Taste tests are often conducted as blind studies. Why? It has been shown that people who are told the brands of the drinks they’re tasting tend to say better things about the brands they’re more familiar with. 1