For example, if a doctor tells a non-smoking, slightly overweight 50-year-old he has an 8% chance of having a heart attack, the patient may think, “Well, I don’t smoke, so it’s probably less for me.” The only problem is that the 8% already takes that into account. Similarly, when a resident of Atlanta hears a climate scientist say that in the next 30 years there’s a 2% chance a climate catastrophe will strike their city, they may think, “Well, we’re not near any major bodies of water so the chances are probably less than that.” But once again the 2% already takes that into account. […]
Another way people can miscalculate risk is by failing to fully grasp measurements in unfamiliar units. […] For example, an increase from 0 to 500 calories is different than an increase from 500 to 1000 calories. With regular numbers that’s not the case. In different units quantities relate to other quantities in different, non-linear ways. […]
New research shows that terms like “improbable” and “unlikely” are so ambiguous it may not be worth using them at all.