9.4 Describing by Sampling

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• Math Help

A survey is used to gather information about a population without causing a change in the population. For instance, a survey might ask for a person's political party preference and annual income. In an experiment, a treatment is applied to part of a population and the responses are observed. Another part of the population may be used as the control group, which receives no treatment. A factor that can affect an experiment's results is the placebo effect. A placebo is a "fake" treatment that appears to be the real treatment. The placebo effect occurs when a subject reacts favorably to a placebo, even though the placebo has no benefit. For instance, to test a drug, here is one way the experiment could be set up.

• Patients are assigned to different treatment groups through random selection.
• The treatment group receives the drug.
• The control group receives a placebo.
• Both groups are "blind," meaning the patients in each group do not know whether they are receiving the drug or the placebo.
• In some cases, the doctors do not know if the patients are receiving the drug or the placebo. When this is done, the experiment is said to be double blind.
• Consumer Suggestion

Edward Bernays is commonly known as "the father of public relations." He invented many common public relations techniques, including the press release. Check out this video on C-SPAN about the life and career of Edward Bernays to learn more.

• Checkpoint Solution

The question that is most likely to produce more people saying they believe Australians are more sports-minded than Americans is question (a). This is because question (a) is a loaded question. The question expresses the opinion that Australians are more sports-minded than Americans and then asks whether you agree with it. The other two questions are impartial and do not offer an opinion. For a survey, question (c) would be the best question to ask because it offers more choices and does not phrase the question in a yes/no format.

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