Joint effect - Definition and Overview

Joint effect is a logical fallacy of causation in which two things that have a common cause are thought to be cause and effect themselves.

For example, ice cream consumption and murder rates are highly correlated. Now, does ice cream incite murder or does murder increase the demand for ice cream? Neither: they are joint effects of a common cause, namely, hot weather. However, if applied to regions of the former Soviet Union, where ice cream conspumption increases in the winter months this analogy would appear not to apply.

This is a special case of correlation implies causation. In statistics the common cause is called a confounding factor and this fallacy is called a spurious relationship.

External link

• Stephen's Guide: Joint effect (http://datanation.com/fallacies/joint.htm)