Which of the following is not one of the three common errors involving $r$ (correlation)?

• A. Using a scatterplot to visually assess the strength of a relationship
• B. Assuming that $r$ (correlation) implies causation
• C. Ignoring the possibility of lurking variables
• D. Assuming a linear relationship when the association is actually nonlinear

Answer: (A)

Verified step by step guidance

1. Step 1: Understand what correlation measures — it quantifies the strength and direction of a linear relationship between two variables.
2. Step 2: Identify common errors involving correlation: (a) Assuming correlation implies causation, which is a logical fallacy because correlation does not prove one variable causes the other.
3. Step 3: Recognize ignoring lurking variables as a common error, where hidden variables may influence the observed correlation, leading to misleading conclusions.
4. Step 4: Note that assuming a linear relationship when the actual association is nonlinear is an error because correlation only measures linear relationships and can miss nonlinear patterns.
5. Step 5: Understand that using a scatterplot to visually assess the strength of a relationship is not an error; in fact, scatterplots are a recommended tool to explore and visualize relationships before calculating correlation.