In clinical trials of medicines, why one group of volunteers given a placebo?

Question

In clinical trials of medicines, why one group of volunteers given a placebo?

Answer 1

This is known as a control group, and provides data that the clinical trial can be compared to. By taking a placebo, the control group believe they are receiving medication, and so it can differentiate between drugs which work physiologically, and drugs which only work psychologically.

Answer 2

Some people believe that just taking a pill will cure them of whatever malady they are suffering from. Some people who take the placebo actually feel better after taking their 'sugar pill'.

This weeds out the hypochondriacs and give the Testers a more accurate analysis if the drug in the test actually does what it is supposed to do.

Answer 3

Just so they know that the medicine works and that they arnt faking it...  Thats basiclaly the only reason... is to see if people are faking it.