What is required to establish causation according to the material?

• A. A large sample size.
• B. A strong correlation coefficient.
• C. Evidence of a causal mechanism.
• D. A random sampling error.

Answer: (C)

Showing a causal mechanism is what makes a causal claim credible. It demonstrates the process by which the proposed cause leads to the effect, providing a plausible sequence of steps that connect the two variables. This moves the relationship from simple association to a real causal link, helping to rule out alternative explanations like confounding factors or chance. For instance, if a program is linked to better outcomes, explaining how the program changes skills or behaviors that directly drive those outcomes gives a believable path from cause to effect. Without a mechanism, a strong correlation could reflect other factors or randomness rather than a true causal influence. Large sample size improves precision but doesn’t establish cause; a strong correlation shows association but not the causal process; random sampling error concerns representativeness, not the causal connection. Therefore, evidence of a causal mechanism is the best evidence for causation.