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Clinical Research Trial (CRT)

A clinical research trial is a research in which an experimental design is used. In such a design the results of an experimental and a control group are compared to each other.


This type of research design is highly valued by scientists. It compares the data from an experimental and a control group before and after an event occurred. This design is depicted in this graphical model:

                                           t1                t2     
Group A     R or M            O1      X      O2
Group B     R or M            O1              O2

It simply says: this research is done by collecting data at two moments. The first moment is before an experimental event occurred and the second one is after this occurrence. Both groups are carefully selected. Though the term group is used, nothing has been said about the size of the group; the minimum could be even 1 so it is even applicable on qualitative research or on comparing two case studies.


Using a placebo

It is not ethical to withhold people medicine when they are ill. But if you give them the same treatment too, the effect of the treatment cannot be tested. Then the control group should get the treatment as usual. In the design this can be stated as:

                                           t1                t2     
Group A     R or M            O1      X      O2
Group B     R or M            O1    TaU    O2

The effect of the new medicine now is tested against the usual treatment.

Sometimes the medicine is expected to work, just because people know they are selected for a special treatment. Now the effect of the treatment is mixed up with the expectations of the members. To unravel this clutching, a placebo is used. A placebo is giving the member of a group a similar treatment but not the one of which an effect is expected. In the design this can be stated as:

                                           t1                t2     
Group A     R or M            O1      X      O2
Group B     R or M            O1      P      O2


Related topics to clinical research design:

  • Design
  • Explorative research
  • Descriptive research
  • Comparative research
  • Evaluation research
  • Longitudinal research

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  • Matching

Deepen your knowledge about cresearch designs in our paper:

How to create research designs and conceptual models.

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