Which term describes the extent of a linear relationship between two variables?

The term that describes the extent of a linear relationship between two variables is correlation. Correlation measures how strongly two variables are related, indicating whether an increase or decrease in one variable tends to correspond with an increase or decrease in another variable. It provides a numerical value, typically ranging from -1 to 1, where values close to 1 imply a strong positive linear relationship, values close to -1 imply a strong negative linear relationship, and a value of 0 suggests no linear relationship.

While causation explores whether one variable directly affects another, it does not quantify the strength of a relationship. Regression, on the other hand, is a statistical method used to model the relationships between variables, often used to predict the value of one variable based on another, rather than simply describing the extent of a linear relationship. Variance refers to how much a set of numbers varies from its average, which does not directly relate to measuring the strength of a relationship between two variables. Thus, correlation is the most appropriate term to describe the extent of a linear relationship.