This is a superbly fun topic!
Causality – the notion of cause and effect. The first thing causes the other and the other is caused by the first.
Correlation – Two items occurring together or seen together.
Correlation is easy. You do a ‘rain-dance’ on Tuesday and it rains. This is a correlation. The world gets this wrong all the time. Some people see causality. The world easily offers you correlations between things. It is much harder to find causality.
Comparing two cities you notice one has more crime. You want to find out why. You observe that the city that has more crime also has more police. You decide that more police equals more crime. You think you have found the cause.
It can get even messier. Let’s say that data was collected over the next year in that city and it was shown that both crime fell and the amount of police fell. That could lend credibility to those that think and know that police numbers cause crime numbers. They would tote that statistic around all day. Proof, I tell you, proof! This fascinating position is aided by confirmation bias and cognitive dissonance. (see my post on all that here) Continue reading →