Noncausal Covariation

Although correlation is a necessary condition for causation, it is not a sufficient condition. That is, if X and Y can be shown to correlate, it is possible that X may cause Y or vice versa. However, just because correlation is established between the two variables, it is not certain that X causes Y or that Y causes X. In instances when X and Y are correlated but there is no empirical evidence that one causes the other, a researcher is left with a finding of noncausal covariation. A researcher [Page 514]can speculate that one variable causes the other, but unless there is empirical evidence demonstrating an internally valid casual relationship, the researcher has no solid ground upon which to claim the relationship is causal.

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