6.15 Testing a natural remedy. The statistical controversy presented in this chapter discusses issues surrounding the efficacy of natural remedies. The National Institutes of Health at last began sponsoring proper clinical trials of some natural remedies. In one study at Duke University, 330 patients with mild depression were enrolled in a trial to compare Saint-John’s-wort with a placebo and with Zoloft, a common prescription drug for depression. The Beck Depression Inventory is a common instrument that rates the severity of depression on a 0 to 3 scale.