But John Ioannidis has found that they can reflect the bias of the person putting them together. Ioannidis has spent his career looking at the published results of medical studies. He thinks that as much as 90% of the published medical reports have enough problems so that one should not place much faith in them.
There are a number of reasons why he considers most medical studies flawed. Often there are an insufficient number of the right type of cases considered. Researchers don't ask the right questions in the right way. But the most common problem is bias. In his view “There is an intellectual conflict of interest that pressures researchers to find whatever it is that is most likely to get them funded.”
Ioannidis is particularly struck by the number of studies whose conclusions are reversed by later studies. He looked at 49 of the medical journal articles most widely cited; 45 of these articles claimed success in the approach taken by the authors with regards to a particular disease. When 34 of these claims were retested, 14 (41%) of these were shown to be far from the success promulgated in the original articles.
However, Ioannidis is not a pessimist. The article concludes with this quote from him. “Science is a noble endeavor, but it’s also a low-yield endeavor,” he says. “I’m not sure that more than a very small percentage of medical research is ever likely to lead to major improvements in clinical outcomes and quality of life. We should be very comfortable with that fact.”
There are a number of reasons why he considers most medical studies flawed. Often there are an insufficient number of the right type of cases considered. Researchers don't ask the right questions in the right way. But the most common problem is bias. In his view “There is an intellectual conflict of interest that pressures researchers to find whatever it is that is most likely to get them funded.”
Ioannidis is particularly struck by the number of studies whose conclusions are reversed by later studies. He looked at 49 of the medical journal articles most widely cited; 45 of these articles claimed success in the approach taken by the authors with regards to a particular disease. When 34 of these claims were retested, 14 (41%) of these were shown to be far from the success promulgated in the original articles.
However, Ioannidis is not a pessimist. The article concludes with this quote from him. “Science is a noble endeavor, but it’s also a low-yield endeavor,” he says. “I’m not sure that more than a very small percentage of medical research is ever likely to lead to major improvements in clinical outcomes and quality of life. We should be very comfortable with that fact.”