References
Statins and risk

Abstract
George Winter considers the nature of risk and how statistics might be used to gain the trust of some, while losing the trust of others
In support of his view that overconfidence could be endemic in medicine, Nobel laureate Daniel Kahneman wrote: ‘Experts who acknowledge the full extent of their ignorance may expect to be replaced by more confident competitors who are better able to gain the trust of clients’ (Kahneman, 2011: 263).
Let us consider how statistics might be used to gain the trust of some … at the possible cost of losing the trust of others. Take, for example, Professor Sir David Spiegelhalter, who addressed a claim made in 2015 by the International Agency for Research in Cancer (IARC) that consuming 50 g of processed meat daily was associated with an 18% increased risk of bowel cancer (Spiegelhalter, 2019: 31).
The 18% refers to a relative risk (RR), representing the increased risk of getting bowel cancer between a group of people who consume 50 g of processed meat daily, and a group who don't. But it ignores absolute risk (AR), ‘which means the change in the actual proportion in each group who would be expected to suffer the adverse event’ (Spiegelhalter, 2019: 32). Thus, normally around six in 100 people (6%) who don't eat processed meat would contract bowel cancer. However, according to the IARC, if 100 similar people ate 50 g of processed meat daily, 18% more would get bowel cancer. An 18% relative increase over 6% is 6% x 1.18 = 7.08%; i.e. one extra case of bowel cancer in 100 lifetime processed meat eaters. This one extra case, observes Spiegelhalter (2019), ‘does not sound so impressive as the relative risk …’
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