A field guide to the ways reasoning breaks
Causal errors
Also called Cum hoc ergo propter hoc
Reading a statistical association as proof that one variable drives the other.
Ice cream sales track drownings, so ice cream drowns people.
Look for a third factor that could produce both, and check whether the direction could be reversed.
Often given in Latin as 'cum hoc ergo propter hoc', 'with this, therefore because of this'. The warning that correlation is not causation became a fixture of statistics teaching in the twentieth century, alongside famous spurious pairings like ice cream sales and drownings, both driven by hot weather.
Schools with more music programs get better test scores, so music must be raising the scores — not the neighborhoods that fund both.
Countries that eat the most chocolate win the most Nobel prizes, so chocolate makes you smarter.
Our most engaged users are also our highest payers, so let's make everyone more engaged and revenue will follow.
Cities with more police have more crime, so adding police clearly causes crime.