I recently penned a post detailing the difference between relative and absolute risk (link). On Friday, March 23 the Wall Street Journal highlighted a similar article on the subject by “The Numbers Guy” Carl Bialik (see his blog post here). If you need something to help you fall to sleep this evening I encourage you to take a read (link is here, subscription may be necessary).
On a serious note, though, the article highlights the recently published study by Harvard scientist on the dangers of eating processed red meat. The authors of this study report how life expectancy declines as consumption of red processed meat increases. They report their results in terms of relative risk and do not mention the absolute risk. Often in science this common due to the many different factors that makes reporting the absolute risk very difficult; however, when the media gets their hands on the published output the message gets convoluted. This was the case with the Harvard study. The study found that (quoting Mr. Bialik’s article):
“A study by public-health researchers, including several from Harvard University, found that eating one additional serving of processed red meat each day is associated with an increase in the risk of death each year by 20%.”
On the other hand, the absolute measure means something quite different (again from Mr. Bialik’s article):
“Prof. Spiegelhalter, analyzing the red-meat results for the British Broadcasting Corporation, determined that if eating red meat really does shorten life instead of merely being associated with higher death rates, the results translate into a typical 40-year-old man in the study living to 79 instead of 80 if he chooses to add a hamburger a day to his diet. That extra year may not seem worth the change in diet to some red-meat fans.”
Just more food for thought… Happy snoozing!