Sunday, August 26, 2007

Innumeracy. What's that!

Innumeracy, a term coined by cognitive scientist Douglas R Hofstadter in the early 1980’s, is a term meant to convey a person's inability to make sense of the numbers that run their lives.

Gerd Gigerenzer, in his book Calculated Risks: How to Know When the Numbers Deceive You clearly demonstrates that innumeracy is common among physicians, and is exploited by medical vendors. (Italic emphasis added by B Davis)

The book is reviewed in the Journal of American Physicians and Surgeons Volume 9 Number 1 Spring 2004. Exerpts follow with the whole review found at

“The object of this book was to clear the mist from typically misleading, if not fraudulent, claims for the effectiveness of drugs and the accuracy of clinical assays. Gigerenzer’s focus is on deceptive presentation of data, usually in the form of relative risk (RR) rather than absolute risks or number needed to treat (NNT).

Gigerenzer points out with many examples that relative risk is always a larger number than absolute risk. One example is a 5-year study of pravastatin.the anticholesterol drug Pravachol.vs. placebo. All-cause death was said in the original paper to be reduced by 22% (RR=0.78). Would you prescribe it? The absolute change was 0.9%, or just 0.18% per year! Would you still prescribe it? It is also known that studies of drugs sponsored by their maker are biased, so even the 0.9% was probably exaggerated.”

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