Control
A control is something against which we make a comparison. If we put large amounts of manure on our roses (an experimental group), we might want to find out what happened to roses on which no manure was used (control group). There can be all sorts of types and names for controls, some appropriate, others not.
- In clinical trials comparing two or more interventions, a control is a person in the comparison group that receives a placebo, no intervention, usual care or another form of care.
- In case-control studies a control is a person in the comparison group without the disease or outcome of interest.
- In statistics control means to adjust for or take into account extraneous influences or observations.
- Control can also mean programs aimed at reducing or eliminating the disease when applied to communicable (infectious) diseases.