A scientist plans to find out if dams harm a river ecosystem. He interviews 500 environmentalists and 450 of them believe that dams are harmful for the ecosystem. The scientist concludes that 90 percent of people believe that dams are harmful. Why is the scientist's conclusion most likely unreliable?

The scientists' conclusions are most likely unreliable because he asked the wrong set of people for his survey. By definition, environmentalists are those people who are inclined to believing that humans are entirely responsible for creating biological foot prints all over the Earth. They always advocate the protection of the environment and even persuade people to follow suit. It is natural for them to react in such a manner that they find dams as something harmful because to them, dams destroy the natural cycle of Mother Earth.