Association is not causation

In economics, identifying cause-and-effect relationships is very important. But statistical association alone cannot establish this causation. Perhaps an extreme example will illustrate the point. Suppose that each November a witch doctor performs a voodoo dance designed to summon the gods of winter, and that soon after the dance is performed, the weather in fact begins to turn cold. The witch doctor’s dance is associated with the arrival of winter, meaning that the two events appear to have happened in conjunction with one another. But is this really evidence that the witch doctor’s dance actually caused the arrival of winter? Most of us would answer no, even though the two events seemed to happen in conjunction with one another.
Those who argue that a causal relationship exists simply because of the presence of statistical association are committing a logical fallacy known as the post hoc propter ergo hoc fallacy. Sound economics warns against this potential source of error.