Drug studies with Vioxx found that 0.75% people on a placebo got heart attacks and strokes, vs. 1.5% who used Vioxx. The article stated that Vioxx caused a doubling of the risk, as

1.5 / 0.75 is 2. What it is actually saying is that out of 100 people, 0.75 more would get a heart attack or stroke. Saying 0.75 more would get a heart attack or a stroke does not sound as bad as saying the risk is double, even though both statements are correct!

 

The statement given in the news media is actually misleading. If we have to make a decision whether or not to take a certain drug, we do not care if the risk is double than the placebo. We merely care that the risk is larger than the margin of error. What we care about is what would happen to 100 people who take the drug. For example, suppose the risk with the placebo were 0.25%, and with the drug 1.00%. Here the risk is four times as large as the risk with the placebo. However, out of 100 people, 0.75 more would suffer. This is exactly the same as the above example with the double risk!

 

This can be given to illustrate how the news media present information which although may be factually correct, does not convey the proper informative content.