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The ‘placebo’ design

A patient’s belief that he is receiving treatment can play an important role in his recovery from an illness

even if treatment is ineffective. This psychological effect is known as the placebo effect. A placebo design attempts to determine the extent of this effect. A placebo study involves two or three groups, depending on whether or not the researcher wants to have a control group. If researcher decides to have a control group,

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  the first group receives the treatment,
  
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  the second receives the placebo treatment and
  
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  the third – the control group – receives nothing
  

The decision as to which group will be the treatment, the placebo or the control group can also be made through randomization.