Correlation

Correlation and causation

"Correlation does not imply causation" is a phrase used in statistics to point out that a correlation between two variables should not imply that one variable has not caused a change in the other. It is a logical fallacy to assume that correlation implies causation.

The following is a flawed argument:

1. Event A occurs in concurrence with Event B
2. Therefore, Event A causes Event B

This is flawed because:

1. There may be a confounding factor causing A and B
2. B may cause A
3. The relationship may be a complete coincidence

Examples

1. As sales of ice cream rise, so do reports of shark attacks
2. High sales of ice cream cause shark attacks

Flaw: Shark attacks and ice cream sales follow a seasonal pattern. Both rise in the summer months. The seasons are a confounding variable.

1. Since the construction of a stadium began in Alaska, the value of your home in Texas has risen
2. Stadium construction in Alaska causes higher home values in Texas

Flaw: This is a coincidence between unrelated variables.

References

• Texas A&M University