What measure indicates the strength and direction of the relationship between two variables?

The measure that indicates both the strength and direction of the relationship between two variables is correlation. Correlation quantifies how two variables move in relation to one another, providing a value between -1 and 1. A correlation value close to 1 implies a strong positive relationship, meaning that as one variable increases, the other does as well. Conversely, a value close to -1 indicates a strong negative relationship, where one variable increases as the other decreases. A correlation value of 0 suggests no linear relationship between the variables.

This concept is central in statistics, as it helps analysts and researchers understand the nature of relationships within data sets. Understanding correlation allows for predictions about one variable based on the behavior of another and helps in identifying patterns that might be useful in various fields such as economics, psychology, and natural sciences.