Funding sources can also subtly create built-in biases. Scientists bristle at the suggestion that taking money from drug companies can influence their results. Yet research has consistently shown that studies of new treatments or drugs were much more favorable when funded by drug makers than other sources such as the federal government. Similarly, two weeks ago, a study in the Journal of the American Medical Assn. revealed that the herbal supplement St. John's wort wasn't effective in treating major depression. But the fine print at the end of the journal article, where researchers disclose their monetary ties, should have given readers pause.
People can use science for or against any point of view they want to promote.
Sometimes, it's not possible to do the neatly designed double-blind studies. You can't assign someone randomly to be obese, or to smoke, or even to take up exercise. Epidemiological research, however, is not definitive. Consequently, if one of these mammoth studies yields an intriguing, statistically significant link, researchers will study it further. The beta carotene controversy is a good example.