“WHAT DOES IT MEAN THAT SOMETHING CAUSES 16% OF CANCERS?”

“WHAT DOES IT MEAN THAT SOMETHING CAUSES 16% OF CANCERS?” This very helpful article by Ed Yong is entitled: “What does it mean that something causes 16% of cancers?” Yong explains the meaning of a study of other study which concludes that 16 per cent of cancers around the world were caused by infections. Yong says that numbers like these “are the results of statistical models that mash together a lot of data from previous studies, along with many assumptions.” It’s a very good description of a lot of statistical work. (Yong has another description of the process that was used for the 16% estimate: Take data from many different sources and: “Bung these all into one statistical pot, simmer gently with assumptions and educated guesses, and voila – you have your numbers.”) What do numbers lie this mean? The data is for all kinds of cancers and all kinds of infections. Yong says that the usefulness is to determine an order of magnitude: “In the case of infections, the message is that they cause more cancers than people might expect.”