Statistical studies often involve several kinds of experiments: treatment groups, control groups, placebos, and blind and double-blind tests. An experiment is a study that imposes a treatment (or control) to the subjects (participants), controls their environment (for example, restricting their diets, giving them certain dosage levels of a drug or placebo, or asking them to stay awake for a prescribed period of time), and records the responses.
The purpose of most experiments is to pinpoint a cause-and-effect relationship between two factors (such as alcohol consumption and impaired vision; or dosage level of a drug and intensity of side effects). Here are some typical questions that experiments try to answer:
Does taking zinc help reduce the duration of a cold? Some studies show that it does.
Does the shape and position of your pillow affect how well you sleep at night? The Emory Spine Center in Atlanta says yes.
Does shoe heel height affect foot comfort? A study done at UCLA says up to one-inch heels are better than flat soles.
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