Statistician: Two major studies found no causal link between medical procedure X and disorder Y, but these studies are flawed  One study looked at 1, 000 people who had undergone procedure X and the other study looked at 1, 100 people who had undergone procedure X  But because disorder Y occurs in only 
02 percent of the population, researchers would need to include many more than 1, 100 people in a study to detect even a doubling of the rate of disorder Y
The two studies cited did not reach a conclusion as to whether disorder Y results from procedure X.