Changes

A placebo is a substance or treatment that has no effect on human beings, but is used as a decoy in studies for the "control" part of the sample.  In other words, part of the study group will receive a placebo, and the remainder the group will receive the new medication being studied, so that the differences in outcome may be compared.

A placebo is a substance or treatment that has no effect on human beings, but is used as a decoy in studies for the "control" part of the sample.  In other words, part of the study group will receive a placebo, and the remainder the group will receive the new medication being studied, so that the differences in outcome may be compared.<ref>http://www.cdc.gov/vaccines/about/terms/glossary.htm#p</ref>