Carbon dioxide levels in the atmosphere are increasing. Fossil fuel use is increasing. Knowing just these two facts and no other information, what is this?

Question 1 options:

Correlation

Both

Causation

Correlation

Explanation:

In statistics, when two (or more) variables are associated in a way that when one changes the other (or others) also changes it is said that they are correlated.

When one event is the result of the occurrence of other event then the relationship called causation: one event causes the other event, which in turn is the effect. That is cause - effect relation.

Many times it is difficult to establish the causation of an effect an it requires some kind of tests or formal reasoning.

In the case of the increasing levels of carbon dioxide in the atmosphere and the increaseing use of fossil fuel, we may be tempted to conclude that the use of fossil fuel is the cause of the increasing levels of carbon dioxide in the atmosphere, but the true is that you need some other information to certainly asses the causation relationship: more data or more insight.

How do you know that there is no other situation that is cause of both facts?

In general, when you only know the behavior of two variables, without more information, you cannot determine whether there is causation or not. You would need to run an experiment (a controlled study) or to posses a deeper insight on the matter.