Which of the following is not measured or described by a $r$ (correlation coefficient)?

• A. The direction of the linear relationship between two variables
• B. The strength of the linear relationship between two variables
• C. Whether the relationship between two variables is $+$ (positive) or $-$ (negative)
• D. The slope of the regression line between two variables ($b$)

Answer: (D)

Verified step by step guidance

1. Understand that the correlation coefficient measures the strength and direction of a linear relationship between two variables.
2. Recall that the correlation coefficient ranges from -1 to 1, where values close to 1 or -1 indicate a strong linear relationship, and values close to 0 indicate a weak or no linear relationship.
3. Recognize that the correlation coefficient indicates whether the relationship is positive (both variables increase together) or negative (one variable increases while the other decreases).
4. Note that the correlation coefficient does not provide information about the slope of the regression line, which quantifies the rate of change between the variables.
5. Therefore, the slope of the regression line is not measured or described by the correlation coefficient.