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Glossary

C

control

An experiment in which the subjects are treated as in a parallel experiment except for omission of the procedure or agent under test and which is used as a standard of comparison in judging experimental effects.2

control Group

The standard by which experimental observations are evaluated. In many clinical trials, one group of patients will be given an experimental drug or treatment, while the control group is given either a standard treatment for the illness or a placebo.

controlled Trial

A clinical study that includes a comparison (control) group. The comparison group receives a placebo, another treatment, or no treatment at all.1

P

Placebo controlled Study

A method of investigation of drugs in which an inactive substance (the placebo) is given to one group of participants, while the drug being tested is given to another group. The results obtained in the two groups are then compared to see if the investigational treatment is more effective in treating the condition.

R

Randomized controlled Trial

A clinical trial in which the subjects are randomly distributed into groups which are either subjected to the experimental procedure (as use of a drug) or which serve as controls2 (See clinical trial)

U

Uncontrolled study

A clinical study that lacks a comparison (i.e., a control) group.1


Glossary Sources

1 NIH.gov
2 Merriam-Webster Dictionary
3 Medline Plus
4 Mayo Clinic
5 CMS.gov