A scatter plot reveals a strong positive linear relationship between two variables. Which of the following is the most appropriate statistical measure to confirm this observation?

The correlation coefficient (often denoted as "r") quantifies the strength and direction of a linear relationship between two variables. A strong positive correlation (e.g., r = 0.9) indicates that as one variable increases, the other tends to increase as well. For instance, a high correlation between advertising spend and sales confirms their strong linear relationship, observed in the scatter plot. This metric is critical for assessing relationships before performing regression or predictive modeling. Why Other Options Are Wrong : A) Standard deviation measures variability, not relationships. C) Mean difference compares group averages, not correlations. D) P-value tests hypotheses but doesn’t quantify relationships. E) Variance measures the spread within a single variable, not between two.