Edmunds Vanags retweetledi

Big headlines the other week about this huge (1.8 million people, 3 continents! Wow!) study out of Oxford looking at the effect of different diets on cancer risk. Vegetarianism cures cancer!!!
Just one problem. That's not what the data show.
The study (nature.com/articles/s4141…) makes it's big claims based on unadjusted p-values (that aren't even numerically reported anywhere in the main paper).
But as anyone with a brain knows, performing 80 different hypothesis tests is bound to produce some false positives. The authors adjust for false discoveries, but don't really take it into account when discussing their data. They also perform sensitivity analysis, but again ignore the findings when discussing their results.
Journalists then picked up the narrative-convenient "significant" findings (while simultaneously ignoring inconvenient significant findings):
BBC, Sky News, The Independent all reported the same claim: "A vegetarian diet can slash the risk of five types of cancer by as much as 30%, a new study has found.”
Okay. But of the original 11 nominally significant findings in study, which made it through both multiple comparisons adjustment and sensitivity analysis?
Just the one.
Which one?
Risk of oesophageal squamous cell carcinoma in vegetarians versus meat eaters. HR=1.93 (95% CI: 1.30-2.87). Yup.
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