This procedure is utilized to prevent bias in research results.
Double-blind studies are particularly useful for preventing bias due todemand characteristicsor theplacebo effect.
For example, let’s imagine that researchers are investigating the effects of a new drug.
Illustration by Emily Roberts, Verywell
In a psychology experiment, the treatment is the level of the independent variable that the experimenters are manipulating.
In such studies, researchers may use what is known as a placebo.
The placebo pill is given to participants who arerandomly assignedto the control group.
A control group is a subset of participants who are not exposed to any levels of theindependent variable.
This group serves as a baseline to determine if exposure to the independent variable had any significant effects.
Those randomly assigned to theexperimental groupare given the treatment in question.
Data collected from both groups are then compared to determine if the treatment had some impact on thedependent variable.
The rest of the subjects will receive an inactive placebo.
Double-blind experiments are simply not possible in some scenarios.
Reasons to Use a Double-Blind Study
So why would researchers opt for such a procedure?
There are a couple of important reasons.
The double-blind procedure helps minimize the possible effects of experimenter bias.
One of the reasons for this is the fact that random assignment reduces the influence of confounding variables.
The researchers might begin by forming a pool of participants that are fairly equivalent regarding athletic ability.
Some participants are randomly assigned to a control group while others are randomly assigned to the experimental group.
Participants are then be asked to eat an energy bar.
The real energy bars contain high levels of protein and vitamins, while the placebo bars do not.
The participants then complete a predetermined athletic task, and researchers collect data performance.
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New York: John Wiley & Sons; 2010.
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Boston, MA: Cengage Learning; 2017.
