Quote by Lance Dodes

“Human research tends to cleave into two major “kingdoms”: observational studies and controlled studies. Observational studies observe and compare groups of people. This research is conducted passively; in other words, without interventions or controls. Any significant differences that emerge between the populations studied—say, finding that people who drink more diet soda tend to have a higher incidence of depression than people who don’t—can’t prove anything but may be used to generate hypotheses about what is causing this difference. Yet people still assume the obvious when confronted with a correlation of this sort. In the diet soda study, which was actually run by the National Institute of Health and widely reported, many people jumped to the conclusion that depression must be caused by something in the soda. But a moment of creative consideration turns up several other plausible possibilities. What if the people who drink diet soda are simply more judgmental about their body appearance and generally more prone to self-criticism? What if, since drinking more diet soda correlates with a history of being overweight, the depression arises physiologically from the effects of obesity, or as a result of the cluster of health problems that go along with it, such as obstructive sleep apnea and diabetes? What if people who are depressed simply crave sweet things, as evidence suggests? And what of the fact that diet soda drinkers tend to cluster more in urban areas: is there something about this environment that promotes depression? Strong correlation is tantalizing, a just-so homily that satisfies our need for simple explanations. It feels definitive and self-apparent, especially given the huge number of subjects typically involved in such studies. The NIH study that produced the diet soda finding, for instance, had 260,000 subjects. Headlines are driven and public health advice administered whenever a major observational study unearths a provocative new correlation. But it turns out that the record of observational studies like these for generating accurate medical advice is, in a word, abysmal.”

Quote by Lance Dodes