In general, which statement about correlation is correct when deciding whether a relationship is causal?

• A. No correlation, by itself, demonstrates causation; establishing causation requires a well-designed experiment or strong causal evidence beyond correlation.
• B. A strong correlation by itself proves that one variable causes the other.
• C. Any correlation found in a scatterplot implies a causal relationship.
• D. Only a negative correlation indicates a causal relationship.

Answer: (A)

Verified step by step guidance

1. Understand that correlation measures the strength and direction of a linear relationship between two variables, but it does not imply causation by itself.
2. Recognize that a strong correlation (positive or negative) indicates association but does not prove that changes in one variable cause changes in the other.
3. Know that no correlation means there is no linear relationship, but this alone does not demonstrate causation or lack thereof.
4. Learn that establishing causation requires additional evidence, such as results from a well-designed experiment or strong theoretical justification beyond just observing correlation.
5. Conclude that the correct statement is: No correlation, by itself, demonstrates causation; establishing causation requires a well-designed experiment or strong causal evidence beyond correlation.