A Different Truth Can Be Hiding Behind Statistics
- 26 march 2009
Journalist Michael Blastand has written an interesting, simple but eye opening article that explains the correct way to think about all the scary “statistics” thrown around haphazardly in the news so often. He explains just how percentages mean nothing unless put into proper context.
We see risk statistics in news articles every day. “One extra unit of alcohol a day increases a woman’s risk of breast cancer by 12%.” “Bacon increases your risk of colorectal cancer by 20%.” But what do those numbers really mean? (Beyond wide-eyed alarmism from the news media, I mean.) Michael Blastland (BBC) suggests converting these risk percentages to the number of additional (or fewer) cases amongst a static population. In his Risk-o-Meter, the statement “Bacon increases your risk of colorectal cancer by 20%” is converted to “about one extra case in every 100 people”. It makes sense: it’s really difficult to make sense of these risk numbers without knowing the prevalence of the disease (…, event, whatever) in the first place.