What is the control group?

What is an experimental group and a control group?

• the definitions are: experimental group: that receives the experiment treatment control group: that doesn't receive experimental treatment what is the meaning of both these groups? i don't get it

• Answer:

  The reason for using a control group is to prove your conclusions are the results of the treatment and to remove personal bias by the subjects being treated. This is called a blinded study. Why should this be done? To remove the power of suggestion from the results. If you tell someone that you have a good medication for a headache 40% or more of the test subjects will report that the treatment significantly reduced their headache ... even though the tablets only contained starch and no active ingredient. That sort of bias can destroy the value of your research. What we do to test for bias is to split people up into 2 or more test groups. The treatments are made to look and taste identical. One group get the real medication the other group gets the blank without the medication. Neither group knows whether they are in the group getting the medication or the blanks. Now you can compare the results of the treatment in the two groups and see if there is a clinically significant statistical difference in the results. This type of test (using a control group) is the minimal level required to analyze data. Better would be to set it up as described then repeat the experiment and reverse the groups based on what treatment they received the first time and re-compare the results. The ultimate standard is to use a double blinded cross-over study. Both groups are tested with blanks and the real treatment and then reversed and on top of that, the administrators of the treatments are also clueless as to which treatment actually has active ingredients or not. This way you remove bias from the patient and bias from the researcher. This is actually the gold standard for running tests on pharmaceuticals in the United States.