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Types of Blinding in Clinical
Research
soumyapottola@gmail.com | https://clinicalda.blogspot.com
Blinding Blinding is a procedure in which one
or more parties in a trial are kept
unaware of which treatment arms
participants have been assigned to,
in other words, which treatment was
received
Types of Blinding ● Single Blinding
● Double Blinding
● Triple Blinding
● Open Blinding
Single Blinding If participants know whether they
were assigned to the treatment or
control group, they might modify
their behavior as a result, potentially
changing their eventual outcome.
In a single-blind experiment,
participants do not know which
group they have been placed in until
after the experiment has finished.
Single blinding
example
You have developed a new flu vaccine. In order to test the
effectiveness of your new treatment, you run an experiment,
giving half of your participants the flu vaccine and the other
half a fake vaccine that will have no effect (to control for the
placebo effect).
If participants in the control group realize they have received
a fake vaccine and are not protected against the flu, they
might modify their behavior in ways that lower their chances
of becoming sick – frequently washing their hands, avoiding
crowded areas, etc. This behavior could narrow the gap in
sickness rates between the control group and the treatment
group, thus making the vaccine seem less effective than it
really is.
To prevent such an outcome, in a single-blind study, you hide
from the participants which vaccine – real or fake – each of
Double Blinding
When the researchers administering the
experimental treatment are aware of each
participant’s group assignment, they may
inadvertently treat those in the control group
differently from those in the treatment group.
This could reveal to participants their group
assignment, or even directly influence the
outcome itself.
In double-blind experiments, the group
assignment is hidden from both the participant
and the person administering the experiment.
Double Blinding
Example
In the flu vaccine study that you are running, you have
recruited several experimenters to administer your vaccine
and measure the outcomes of your participants.
If these experimenters knew which vaccines were real and
which were fake, they might accidentally reveal this
information to the participants, thus influencing their
behavior and indirectly the results.
They could even directly influence the results. For instance, if
experimenters expect the vaccine to result in lower levels of
flu symptoms, they might accidentally measure symptoms
incorrectly, thus making the vaccine appear more effective
than it really is.
To avoid this, you hide group assignments from both the
participants and the experimenters giving the vaccines – a
double-blind study.
Triple blinding Although rarely implemented, triple-blind
studies occur when group assignment is
hidden not only from participants and
administrators, but also from those tasked
with analyzing the data after the experiment
has concluded.
Researchers may expect a certain outcome
and analyze the data in different ways until
they arrive at the outcome they expected,
even if it is merely a result of chance.
Triple blinding
Example In your vaccine study, you have also
recruited assistants to analyze the data you
gathered on flu infection rates. You decide to
hide the group assignments from the
participants, the people administering the
experiment, and the people analyzing the
data – a triple-blind study.
To achieve triple blinding, you assign each
participant to group 1 or group 2, but do not
inform the data analysts which number
represents which group.
Single blind V/S
Double blinding
Open Blinding Open Blinding is a procedure in
which parties in a trial are kept
aware of which treatment arms
participants have been assigned to,
in other words, which treatment was
received.
Open Blinding OPEN TRIAL LABEL

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Types of Blinding in Clinical Research..

  • 1. Types of Blinding in Clinical Research soumyapottola@gmail.com | https://clinicalda.blogspot.com
  • 2. Blinding Blinding is a procedure in which one or more parties in a trial are kept unaware of which treatment arms participants have been assigned to, in other words, which treatment was received
  • 3. Types of Blinding ● Single Blinding ● Double Blinding ● Triple Blinding ● Open Blinding
  • 4. Single Blinding If participants know whether they were assigned to the treatment or control group, they might modify their behavior as a result, potentially changing their eventual outcome. In a single-blind experiment, participants do not know which group they have been placed in until after the experiment has finished.
  • 6. example You have developed a new flu vaccine. In order to test the effectiveness of your new treatment, you run an experiment, giving half of your participants the flu vaccine and the other half a fake vaccine that will have no effect (to control for the placebo effect). If participants in the control group realize they have received a fake vaccine and are not protected against the flu, they might modify their behavior in ways that lower their chances of becoming sick – frequently washing their hands, avoiding crowded areas, etc. This behavior could narrow the gap in sickness rates between the control group and the treatment group, thus making the vaccine seem less effective than it really is. To prevent such an outcome, in a single-blind study, you hide from the participants which vaccine – real or fake – each of
  • 7. Double Blinding When the researchers administering the experimental treatment are aware of each participant’s group assignment, they may inadvertently treat those in the control group differently from those in the treatment group. This could reveal to participants their group assignment, or even directly influence the outcome itself. In double-blind experiments, the group assignment is hidden from both the participant and the person administering the experiment.
  • 9. Example In the flu vaccine study that you are running, you have recruited several experimenters to administer your vaccine and measure the outcomes of your participants. If these experimenters knew which vaccines were real and which were fake, they might accidentally reveal this information to the participants, thus influencing their behavior and indirectly the results. They could even directly influence the results. For instance, if experimenters expect the vaccine to result in lower levels of flu symptoms, they might accidentally measure symptoms incorrectly, thus making the vaccine appear more effective than it really is. To avoid this, you hide group assignments from both the participants and the experimenters giving the vaccines – a double-blind study.
  • 10. Triple blinding Although rarely implemented, triple-blind studies occur when group assignment is hidden not only from participants and administrators, but also from those tasked with analyzing the data after the experiment has concluded. Researchers may expect a certain outcome and analyze the data in different ways until they arrive at the outcome they expected, even if it is merely a result of chance.
  • 12. Example In your vaccine study, you have also recruited assistants to analyze the data you gathered on flu infection rates. You decide to hide the group assignments from the participants, the people administering the experiment, and the people analyzing the data – a triple-blind study. To achieve triple blinding, you assign each participant to group 1 or group 2, but do not inform the data analysts which number represents which group.
  • 14. Open Blinding Open Blinding is a procedure in which parties in a trial are kept aware of which treatment arms participants have been assigned to, in other words, which treatment was received.
  • 15. Open Blinding OPEN TRIAL LABEL