A placebo is a treatment, most commonly a medication of some kind, which is given to a subject with the pretense that it will treat a specific ailment when in fact the treatment will have no significant effect on the subject. The subject may report that the treatment has had a positive effect, when in fact the effect is entirely in the imagination of the subject. Therefore, a placebo variable is a factor that researchers in the medical field must consider when experimenting with new treatments, to decide whether the success of the treatment is due to the psychological or placebo effect of the treatment, or if the treatment itself is working.