What is Causation?

Correlation is a term that simply implies the existence of a relationship, or statistical association, between variables. Although causation also implies a relationship between variables, it goes farther to define the type of relationship as well. Causal relationships exist only when one variable ‘causes’ a change in the other. 

It is important to note that although causation always implies correlation, correlation does not imply causation. But why?  

For two variables to have a causal relationship, they must have a statistical association, and they must therefore be correlated. However, there are circumstances where correlation does not imply causation. These are a few reasons why correlation does not imply causation: 

• Sometimes even when variables do have a cause-and-effect relationship, there may be directionality issues. Directionality Issues make it hard to determine which variable is the independent variable and which is the dependent variable, making it impossible to conclusively derive causation.
• Another reason why correlation does not imply causation is due to the influence of extraneous/confounding variables. In many cases, although it may seem like two variables are very closely related, they may actually be correlated due to a third variable (or a chain reaction of multiple other variables) that has a causal relationship with each one of the variables individually. Therefore, these variables do not have a causal relationship as their statistical association can be due to the influence of another variable.