How Are Participants Assigned
to Groups?
Doctors use a process called
randomization (chance) using a computer to assign you to either
the intervention group or the control group in Phase III studies.
This method ensures that certain factors and human choices don't
affect study results, making them less reliable. When groups
are compared with each other, it is clear whether the study
agent works or has bad side effects. This also helps ensure
that the findings really result from the study  agent, and not from something else.
Most Phase III cancer prevention
studies use a double-blind research design. This means that
neither you nor the doctors know which people are taking the
study agent or the control agent. Only the researchers at a
central office know. Sometimes a doctor needs to find out if
a participant has taken the study agent. A doctor can find this
out, if needed, by talking with the central office staff.
No one knows whether it is
better to be in the intervention or control group until the
study is over and the results are ready. If that were known,
there would be no need for the study. Either group may have
good results or problems. The results help doctors decide whether
to advise people to take the study agent for cancer prevention.
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