What is the most reliable correlation coefficient indicating a perfect relationship?

A correlation coefficient is a statistical measure that describes the strength and direction of a relationship between two variables. The values of the correlation coefficient range from -1 to +1.

A correlation of +1.0 signifies a perfect positive relationship, meaning that as one variable increases, the other variable also increases proportionally. This is why +1.0 is considered the most reliable coefficient indicating a perfect relationship; it shows a direct and consistent pattern between the two variables being analyzed.

In contrast, a value of -1.0 indicates a perfect negative relationship, where one variable increases as the other decreases, which is strong but in the opposite direction. A value of 0.0 indicates no correlation at all, meaning there is no predictable relationship between the two variables. A correlation of 0.5 demonstrates a moderate positive correlation, showing that there is some relationship, but it is not strong or perfect.

Thus, the highest possible value, +1.0, rightly represents the most reliable correlation coefficient for a perfect relationship.