 While clinical medicine is enormously better than it was 100 or even 50 years ago, there remain many diseases against which current clinical medicine offers an inadequate response. To name just a few, malaria kills over a million people, mostly children, every year; chronic diseases, chief among them heart disease and stroke, kill millions each year, and there still are no effective treatments for Alzheimer disease. The social value of clinical research lies in its ability to collect information that might be useful for identifying improved methods to address these conditions. Yet, it is the rare  study which definitively establishes that a particular method is effective and safe for treating, curing or preventing some illness. The success of specific research studies more commonly lies in the gathering of information that, together with the results of many other studies, may yield these improvements. For example, prior to establishing the efficacy of a new treatment for a given condition, researchers typically need to identify the cause of the condition, possible mechanisms for treating it, a safe and effective dose, and ways of testing whether the drug alters the course of the disease.