In statistics, a confounding factor is a factor which is the common cause of two things that may falsely appear to be in a causal relationship. It is the cause of a spurious relationship.

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 or confounding factor, namely, hot weather.

See also

• Spurious relationship
• Joint effect