Base Rate Fallacy
(reading time – 50 sec.)

Base rate neglect is the tendency for people to mistakenly judge the likelihood of a situation by not taking into account all relevant data.

Lots of food companies exploit the Base Rate Fallacy on their packaging. When something says "50% extra free," only a third (33%) of what you're looking at is free. If you think half of what you're looking at is free, then you've committed the Base Rate Fallacy. For example, when you buy six cans of Coke labelled "50% extra free," only two of the cans are free, not three. (It's because the original pack had four cans, and 50% of the original amount is two cans.)

Topic: #CognitiveBiases
Source: howtogetyourownway.com