Which correlation coefficient indicates the strongest relationship between two quantitative variables?

The correlation coefficient quantifies the strength and direction of the relationship between two quantitative variables. The value of the correlation coefficient ranges from -1 to 1. A coefficient close to 1 indicates a strong positive relationship, where an increase in one variable is associated with an increase in the other. Conversely, a coefficient close to -1 indicates a strong negative relationship, where an increase in one variable is associated with a decrease in the other.

In this case, a correlation coefficient of 0.85 signifies a strong positive relationship between the two variables. This means that as the first variable increases, the second variable also tends to increase, and the strength of this relationship is robust. A coefficient of -0.80 represents a strong negative relationship, but since it is negative, it does not indicate a positive association.

The other values, 0.25 and 0.15, indicate weak positive relationships; thus, they are nowhere near as strong as the relationship indicated by 0.85. Therefore, this choice captures the strongest overall correlation between the two variables being analyzed.