Why won't they tell me what I am taking?

Medical research studies on investigational treatments compare the health outcomes of people taking an investigational treatment against those taking a treatment that has already been approved and is in common use (also called the "standard treatment"), or no treatment at all. The people who receive the investigational treatment are called the intervention group and the group who get the standard treatment or no treatment are called the control group or the "placebo group." The word "placebo" means an inactive treatment that is made to look, feel, and taste like the investigational treatment, but does not contain any active ingredient.

The goal of clinical trials is to find out if a new treatment works or does not work. Placebos are used because we know that a portion of the people who receive an investigational treatment will get better just because they believe that taking a pill (or getting other treatment) will make them better. By giving some volunteers a placebo and comparing their response to the response of those volunteers who receive the actual treatment, researchers can find out if the investigational treatment really works.

If you are thinking about volunteering for a study that includes a placebo group, remember that you may not receive the investigational treatment. In fact, you will not know which group you are in until the study is completed.

The scientist and physicians who do this kind of medical research do their best to make sure that their hope for a successful study does not influence the study's results. Scientists refer to this as study bias. One way that this might happen is if the researchers decide who gets to be in the intervention and control groups (like choosing sides for a basketball game). To avoid this bias, study volunteers are assigned to either the intervention or the control group at random. This randomization makes sure that the treatment group and the control group are similar.

Another way that researchers avoid bias is by making sure that the person who knows which treatment (new, standard, or none) a volunteer receives is not the same person who sees the volunteer in the clinic and determines whether the volunteer is doing better or worse. This is referred to as a double-blind study, since neither the volunteer nor the person measuring the effects of the treatment knows which treatment the volunteer is actually getting.