This is a slight exaggeration (and also not true), but you know the headlines that I’m referring to.
Social media posts by viral-seeking pages such as Ladbible, Unilad etc. that are all about engagement. That’s how they get paid after all.
More often than not it’ll be something along the lines of ‘X activity increases the risk of developing Y disease’.
Let’s take this article by ITV from 10 years ago as an example – processed meat can cause cancer.
It states that eating just 50g of processed meat, the equivalent of roughly two slices of bacon, increases the risk of developing bowel cancer by 18%.
After reading this I wouldn’t be surprised if some people threw out all of their red meat & became vegetarian/vegan. 18% sounds like a big difference and of course nobody wants to develop cancer so it would make sense to eliminate all of the potential hazards that they can control.
However, it’s important to understand the difference between relative and absolute risk.
Relative risk describes how much the risk of a disease or outcome changes compared to a baseline. For example, an 18% increase means the risk is 18% higher than normal.
Absolute risk is the actual, real-world chance of that disease or outcome occurring once this increase is applied.
Let’s apply this to the current scenario.
According to Cancer Research UK, the average adult has around a 6% lifetime risk of developing bowel cancer.
The ITV article states that this risk increases by 18% if someone eats 50g of processed meat. Because this is a relative increase, we multiply the baseline risk by 1.18:
6% x 1.18 = 7.08%.
In other words, the lifetime risk increases from about 6 in 100 people to just over 7 in 100 people.
The figures are correct & ITV didn’t lie or fabricate the truth in any way, but can you see how different the information looks just by how it’s presented?
There’s no way that an article titled ‘Likelihood of being diagnosed with cancer jumps from 6% to 7% if you have a bacon sandwich’ would elicit the same emotional response as the original title.
You can apply this to any article you come across in the future. All you need to do is find out the original (baseline) risk of an outcome/disease, multiply it by the figure stated (10% would be 1.10, 20% would be 1.20 etc.) and then you’ll get the true figure which is often far less dramatic than the headline suggests.
I hope this was easy to follow & it made sense!
