Do you have an understanding of what a 'control' or 'control group' is?
A control is the standard by which experimental observations are evaluated. In many clinical trials, one group of patients will be given an experimental drug or treatment, and the control group is given either a standard treatment for the illness or a placebo. If you have worked with clinical trials/observations, you will understand what the 'control' or 'control group' is. If you have not, discuss what you do know. In most cases, an interviewer will know if you already have clinical trial experience and will know where to guide you with a question like this.
"Yes, I understand the importance of a 'control/control group' in trials. I assisted with documentation for a clinical trial when I worked at XYZ. Part of my responsibilities included monitoring the differences in vital signs of the patients who were given a placebo compared to those who were taking the trial drug."
"I am familiar with a control/control group. It is my understanding that when a clinical trial is being conducted, some participants are given the trial drug, and the 'control group' is given either the standard treatment or a placebo, but only the person administering the drug knows who is receiving which."
