What statistical measure is used to assess how different two variables are from one another?

The correlation coefficient is a statistical measure used to assess the strength and direction of the relationship between two variables. It quantifies how much one variable tends to change in response to changes in another variable. A correlation coefficient can range from -1 to +1, where values closer to +1 indicate a strong positive relationship, values closer to -1 indicate a strong negative relationship, and values around 0 suggest no relationship.

This measure is particularly useful in understanding the degree to which two variables are related, which directly addresses the question of how different they are from one another. By assessing the correlation, researchers can determine whether an increase in one variable corresponds with an increase or decrease in another variable, thereby indicating the nature of the difference between them.

In contrast, other options may not directly measure the difference between two variables. The mean difference calculates the average difference between paired observations but does not provide insight into how one variable relates to another across all data points. Standard deviation measures the variability or dispersion of a single variable’s values, not the relationship between two. Finally, regression analysis explores relationships between variables but does so in a more complex way that often entails predicting values rather than simply assessing how they differ.