Medical statistics are often misunderstood (perhaps up to 72.381672 percent of the time).
Sometimes they're consciously spun. More often they're just phrased in an opaque way.
Given all the stories in recent weeks on cancer screening (mammograms, psa tests, pap tests), the effectiveness of medicines, drugs and supplements (statins, tamoxifen, vitamin D), not to mention the focus on the health care bill, it is a good time to briefly discuss a few better ways to present medical results.
Relative Risk vs. Absolute Risk
To make my points general, I'll refer to an abstract cancer X rather than any particular real cancer, which is anything but abstract.
That being said, imagine that a headline announces that screening for cancer X reduces deaths from it by 25 percent. Imagine as well that another headline announces that screening cuts deaths from cancer X by about 1 in 1,000, reducing the rate from 4 in 1,000 to 3 in 1,000. Read more...