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Control Group and Experimental Groups

Control Group and Experimental Groups

Control group: Control groups are not manipulated. They are the foundational point for which to compare the experimental group against. See example given below.

Experimental group: The group being treated, or otherwise manipulated for the sake of the experiment. This group is identical to the control group EXCEPT that it is manipulated.

In the example below, the amount of water is being manipulated. Lets say you want to know the effect of excessive water drinking has on humans. You gather a group of people together and get them to drink a lot of water. This is the experiment group. What ever effects they display you might be inclined to attribute to excessive water drinking. HOWEVER, how do you know that all the symptoms they display are from drinking lots of water? Maybe some of the symptoms they display are totally unrelated to water and are the result of some other factor (like being together in an isolated group.) Therefore, in order to separate excessive water symptoms from other symptoms you gather a second group of people together and place them in exactly the same environment as the first group EXCEPT you do not give them excess water. This is your control group. What ever differences there are between your experimental group and your control group are due solely to excess water.

http://www.holah.karoo.net/experimental_method.htm

Other Resources
http://www.utas.edu.au/sciencelinks/exdesign/C3A.HTM Threats to validity of Research Design http://www.creative-wisdom.com/teaching/WBI/threat.shtml Glossary of Key Terms http://writing.colostate.edu/guides/research/glossary/#internal_validity


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Written by tusksowk

April 7, 2010 at 11:58 am

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