Ben Goldacre's Moment of Genius on BBC4 radio:
"Clinical trials in medicine are designed to be free from bias. They test, as objectively as possible, the effectiveness of a particular intervention.
When you bring the results of all these individual trials together, however, how do you weigh up what evidence is relevant and what is not? In 1993, a method of "systematic review" was introduced that enables us to get the clearest possible view of the evidence."