Lurking Variable???

Question

Suppose that statisticians determine that there is a significant positive correlation between the grade earned in the class College Reading Skills and the grade earned in Statistics. Does achieving a high grade in reading cause an individual to earn a high grade in Statistics? Explain your answer with reference to the term lurking variable.

Answer 1

Correlation does not imply causation. This is a fundamental rule in statistical analysis. A and B may have positive correlation, but it does not necessarily mean that A causes B, or that B causes A.

For example, what if C causes both A and B? Whenever C is present, you will find both A and B, leading to the correlation. In this case, C is the "lurking" variable; the hidden cause of both A and B.

In your example, the third variable would be something like "hard work" or "dedication". Students that are determined and work hard tend to better in both reading classes AND statistics classes, leading to the positive correlation.