 In an RCT, a population of individuals who might benefit from a new medical treatment are divided into a treatment group—the group whose members receive the new treatment—and one or several control groups—groups whose members receive either an alternative or “standard” treatment or a placebo.  Individual patients are assigned to a group by means of a random process such as the flip of a coin. A placebo is an intervention that resembles the new treatment in all respects except that it has no known ingredients active for the condition under investigation (i.e., it is some kind of “sugar pill”). Patients, researchers, nurses, and analysts are all blinded with respect to treatment status of all patients until after the analysis. After a period of time, a pre-determined outcome variable is observed and the values of the variable are compared between the groups. If the value of the outcome variable differs between different treatment groups at the desired level of statistical significance, the treatment is judged to be effective.