Why do industry-funded studies usually support the industry’s products?
According to this article, it's because industry-funded studies ask biased questions:
Wal-Mart and Toys R Us announced this spring that they will stop selling plastic baby bottles, food containers and other products that contain a chemical that can leach into foods and beverages. Even low doses of the chemical (bisphenol A, or BPA) are linked to prostate and mammary-gland changes in laboratory animals that were exposed as fetuses and infants. The big retailers are responding to the fears of parents, and Congress is considering measures to ban the chemical.
But is there enough evidence of harmful health effects on humans? One of the eyebrow-raising statistics about the BPA studies is the stark divergence in results, depending on who funded them. More than 90 percent of the 100-plus government-funded studies performed by independent scientists found health effects from low doses of BPA, while none of the fewer than two dozen chemical-industry-funded studies did.
This striking difference in studies isn't unique to BPA. When a scientist is hired by a firm with a financial interest in the outcome, the likelihood that the result of that study will be favorable to that firm is dramatically increased. This close correlation between the results desired by a study's funders and those reported by the researchers is known in the scientific literature as the "funding effect."
As you read this article, keep in mind that pharmaceuticals and not the FDA run the studies necessary to get a drug approved by the FDA. I wonder if drugs like Vioxx or Trasylol ever would have been approved if the government ran the studies...