A placebo is a treatment of people with an ineffective drug. In this way, the effect of a drug with an expected effect can be compared.
A person who feels sick can receive a medicine that heals. Many diseases also pass on their own, so sometimes it is not necessary to use a medicine. To study the difference in the effect of a medicine, subjects were given a medicine without the active substances in the real medicine. It turned out that these people also recovered faster than those who did not receive medication, but less quickly than those who did receive the right medication. This is called the placebo effect. The placebo is the medicine with the ineffective substances.
Designs with a placebo
The effect might be due simply because a treatment is given. That is why itmakes sense to insert a treatment with a placebo. Now the designs looks like this:
There is no good explanation for the placebo effect. It seems that it is a form of self-affirmation. Because the person expects the drug to work, he also behaves according to those expectations.
Nowadays, when testing medicines, it is necessary to include three groups in the research design: a group that receives the usual treatment, a group that receives the test substance and a group that receives a placebo.
The term placebo is the most used and the most adequate term. Sometimes the term nocebo is used to indicate that the administration of a substance will not have a positive but a negative effect.