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Research Design Discussion

This solution discusses the purpose of control and comparison groups in an experimental study, as well as two of the most important issues or problems in selecting an appropriate control or comparison group.

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RESPONSE:

1. What is the purpose of control and comparison groups in an experimental study?

Experimentation explores cause and effect relationships by manipulating independent variables in order to see if there is a corresponding effect on a dependent variable. Pure experimentation requires both a controlled environment and the use of a randomly assigned control or comparison group. This can be difficult to achieve in human centered experiments conducted in the real-world (http://www.sagepub.co.uk/resources/oleary2/ch6.ppt).

Control group (also referred to as comparison group) is a sample in which a factor whose effect is being estimated is absent or is held constant, in order to provide a comparison (http://www.answers.com/topic/experiment-3?cat=health). The purpose of the control group is to provide a comparison with the experimental group to determine if the factor had a statistical effect (or not). A control group is an essential part of the scientific research method because the purpose is to ensure that any changes observed in an experimental group are due solely to the drug or experimental procedure and not to any other factors (validity issue) (http://www.answers.com/topic/experiment-3?cat=health). The control group, for example, is the group of participants in a clinical study who do not receive the drug or treatment being studied against which the reactions of individuals in the experimental (e.g., do received the drug treatment) group may be compared. It a significant difference between the treatment and control group, then we can say that the treatment had an effect and that is was successful. This is necessary for both internal and external validity of the study.

Example:

For example, when the safety and effectiveness of an exercise program is tested experimentally, it is important to ensure that the observations are due to the factors under consideration, and not to any ...

Solution Summary

What is the purpose of control and comparison groups in an experimental study? What would be two most important issues or problems in selecting an appropriate control or comparison group?

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