The next time someone confuses correlation vs. causation send them this link. If they don’t get it (and instead somehow think this graph proves that organic food causes autism) then you know they are a lost cause anyway.

cau·sa·tion

/kôˈzāSHən/

Noun
  1. The action of causing something.
  2. The relationship between cause and effect; causality.
Synonyms
causality

cor·re·la·tion

/ˌkôrəˈlāSHən/

Noun
  1. A mutual relationship or connection between two or more things.
  2. Interdependence of variable quantities.
Synonyms
interrelation

co·in·ci·dence

/kōˈinsədəns/

Noun
  1. A remarkable concurrence of events or circumstances without apparent causal connection.
  2. Correspondence in nature or in time of occurrence.
Synonyms
concurrence – accident – chance
MORE:
Wikipedia – Correlation does not imply causation
The Atlantic – When Correlation is Not Causation–but Something Much More Screwy
Stumble Upon – Funny Correlations (To Prove the Point)