What does randomization mean for research volunteers?
[Intro] Hello!
The Federal Office for Human Research Protections, or OHRP, created these videos to help you
learn more about participating in research.
Deciding if you want to volunteer for a research study can be difficult, and this decision
can have important consequences.
Research that compares interventions or treatments commonly uses “randomization” as part
of the study design, which means that volunteers are assigned randomly to particular study
“arms,” or groups.
Which intervention or treatment the volunteers receive depends on the study arm they are
assigned to.
This video provides some basic information about why researchers use randomization in
studies and what randomization means to you as a potential research volunteer.
[What does “random assignment” mean?]
When something happens “randomly,” that means it happens completely by chance, and
that no one can predict or control the result.
Drawing numbers out of a hat to separate people into two teams is a random procedure.
So is flipping a coin to decide who goes first in a game.
Randomization is a commonly used procedure in clinical research.
Research volunteers may be randomized to different arms in a study.
This means that a volunteer’s assignment to a particular study arm is by chance, and
that it is not planned or controlled by the researcher, the volunteer’s doctor, or anyone
else.
Which study arm a volunteer ends up in is random, like whether a coin flip comes up
heads or tails, without any input from the study team.
[Why is randomized assignment used in research?]
Researchers use randomized assignment to help get reliable answers to research questions.
Suppose researchers want to know if a new drug can help people fight an infection better
than one already being used.
They enroll volunteers who have the type of infection the drugs are supposed to treat.
Then they randomly assign volunteers to one of two study arms.
In one study arm, volunteers receive a drug that is currently prescribed by doctors.
Volunteers in the other study arm receive the new, experimental drug.
Then researchers collect information about how the volunteers in each group respond to
the different drugs.
If the researchers get to decide who gets which drug and don’t use randomization,
they might unintentionally give people who seem sicker the new drug—perhaps because
they think the new drug might work better, or maybe they would give sicker volunteers
the commonly-used medicine, because they have more experience with it.
But if either of those things happened, the results of the study wouldn’t tell researchers
whether one drug really works better than the other because the volunteers in each arm
are too different from each other.
A difference in results between the two study arms might occur just because one arm includes
sicker volunteers.
To make sure that any differences in results between the study arms are caused only by
the different drugs, the volunteer groups need to be similar in health and other characteristics.
Like the saying goes, it’s important to compare apples with apples.
Randomization is supposed to help make the groups more similar.
When volunteers are assigned randomly to the study arms, no one controls which group a
volunteer will be in.
Therefore, as long as there are enough volunteers, the study arms should be similar.
In our example, each study arm would have roughly the same number of volunteers with
mild and serious infections, and be generally similar in other characteristics.
This way, the only thing that is different between the two groups is the drug they take.
The researchers can be more certain that any differences in the results are caused by the
drugs being studied and not the characteristics of the volunteers in the groups.
This is why randomized studies can produce more reliable results.
Sometimes researchers take additional steps to avoid unintentionally influencing the results.
For example, they may design the study so that volunteers won’t know, or are “blinded”
to, which group they are in.
Other times, both the researchers and the volunteers don’t know which group the volunteers
are in.
This is called a “double-blind” study.
It ensures that no one can intentionally or unintentionally influence the results.
Double-blind randomized studies are one of the best research designs and generally produce
the most reliable results.
[So what does it mean for research volunteers to be “randomized”?]
If you are asked to participate in a research study with a randomized design, here’s what
you need to know: • Your assignment to a particular study
arm or group is done randomly, like a coin flip.
The research team cannot choose which group you end up in.
• Similarly, your doctor cannot choose which study arm you end up in, even if she or he
thinks that one group might be better for you than the other.
Your assignment to a study arm is entirely by chance.
• You also cannot choose which group you are in, and you may not get the one that you
want.
• It is possible that the researcher, your doctor, and you will not know which study
arm you are in, and won’t be allowed to find out as long as the study is still going
on.
• It is important to remember that, unlike medical treatment, research is not designed
to specifically address your needs and interests as an individual patient.
The care that you receive in a research study does not necessarily put your individual interests
first, will not necessarily benefit you, and could even be harmful, even though there are
protections in place.
Research volunteers can help science answer specific medical or behavioral questions.
Researchers hope that these answers will contribute to a better understanding of human biology
and behavior, and lead to more effective medical treatments in the future.
[Closing]
This video was designed to answer some basic questions about randomization in research
and give you some things to think about.
Deciding whether to participate in research can be hard.
Don’t be afraid to ask the research team for more information and talk with them about
your concerns.
It’s their job to give you the information you need so you can make the most informed
decision about whether to participate.
OHRP has created a variety of resources to help you think about research participation.
For more information, check out our website at www dot hhs dot gov forward slash about
dash research dash participation.