Question

Explain the third variable and directionality problems associated with correlations, what spurious correlations are, and how these can make it difficult to interpret correlational evidence.

Answer 1

Correlation studies are none-experimental studies. The variables studied in a correlation study may have a relationship that is increasing in one variable could show an increase or decrease in the other variable, but this may not be because of a causal relationship.

When there is a strong relationship between the two variable, an increase or decrease of a variable is not the cause of an increase or decrease in the other variable but is due the presence of a third variable is called the third variable problem. For example, a study that indicates a positive relationship between gender and talking habit during the lecture could be because of the environment of the class or other factors as disinterest in the class or the teaching method of the teacher.

Similarly, the directionality problem is when two variables are strongly correlated without any a cause. For example, happiness and physical exercise are positively correlated but it couldn't be proved whether the exercise causes happiness or happiness motivate for exercise.

The spurious correlation indicates a relationship between the two variables but it does indicate causation. The reasons for this correlation could be the presence of a third variable or could be a mere coincidence. This, the correlation evidence between two variable cannot be taken for causation, that is a change in one variable cause a change in the other variable.