One of the main research methods in psychology is the correlational design, which observes the amount that two variables are related. A key point in correlation is if two variables are correlated they are related statistically. A cause cannot alone be inferred from a correlational study, although there is sometimes a causal relationship between the two variables. This leads to the correlation versus causation fallacy. In the correlation versus causation fallacy, there is still a correlation present from the two variables, but the relationship between the two is usually mistaken as the two variables having a direct cause on one another. The correlation between variables A and B could be due to an outside variable, variable C. The variable C can be correlated with both variables A and B, but because variable C is not present in the data being observed, it would look as if A and B have a causal relationship when they do not.
This concept of correlation versus causation is important in the correlational study because it gives insight on how variables are related to each other. When a researcher is conducting or looking at a correlational study and are aware of the correlation versus causation fallacy, it allows them to understand the relationship between the two variables and understand that the relationship could be caused by an outside variable.
In this example of a correlational study two variables, global average temperature and number of pirates, are compared. When first looking at this data, it would appear there is a causal relationship that as the average global temperatures increase the number of pirates increase. However, this relationship between variables could be caused from another outside variable. One possible outside variable is that as the global average temperature increases the sea becomes calmer. With the sea being calmer more pirates would want to be out sailing. Without considering this outside variable it would seem as if the global average temperature and the number of pirates have a causal relationship when they do not.