What is the point of a control group in an experiment?

I dont understand why we do one in an experiment. Whats the purpose of having one? What benefits does it give ?|||Without a control an experiment cannot be considered valid. The control shows what happens under normal circumstances, and these results allow you to compare the results from experiments with what would happen normally. Having a control may seem pointless when observing physical properties (for example a control which is just a cup of water on the bench in which case it's obvious that there will be no change), but when you're dealing with numbers you need the results of the control to put your experimental data into perspective and when you perform experiments you need to have a control to determine how much of an impact environmental conditions had on your results.|||I will try to break this down for you. This can be kind of a confusing things to understand, so I know where you are coming from with your question.





I am going to give you an example of how this whole thing works.





Lets say that I claim to have this wonder pill that cures all depression. People are probably not going to believe me without evidence.





I am going to have to prove myself by doing an experiment. I am going to collect a population of people who are depressed.





I am going to call one of my groups and "experimental group". This group will get my pill that cures depression.





I am going to also have a "control group" who will receive a pill that is fake and will NOT cure depression.





I will NOT know who receives my real pill and the people that I am doing the experiment on will also NOT know what pill they are receiving.





We do this so that there is no biased in the experiment. We don't want the people to be aware of what pill there taking because we want to see if my pills made a difference or not.








If the group that takes the pill starts feeling better after taking my pill than we know that my pill works.





If the group that takes the fake pill still feels like crap, than it will prove my point.





If you give 25 real pills out and 25 fake pills out than you need to see how many of them felt better by taking my pills.





A control group is important because they help to prove my point. I want to prove to people that my pill really works. I want to show people that I gave fake and real pills out. If the 25 people that I gave the fake pills to still feel like crap than I prove that my pills work.





I don't want someone to stand their and tell me that the depressed people only started feeling better because they knew that they were going to get better by taking my pills.





If no one knows what pill that they are taking than the people prove my theory for me.








I hope this didn't confuse you more!





hope this helped,





Cordelia








There is also something called the placebo affect. Sometimes the people who take the fake pill, actually start to feel better. This is more psychological than anything else.|||Its just like a neutral..Its used to compare the results we get from samples with the neutral one..so that the effect of the experiment or result can be accurately calculated..|||It gives you something to compare your results with. it can determine if the scientific investigation was a success or failure.