What term describes the relationship between two variables and how well one can predict the other?

The term that accurately describes the relationship between two variables and how well one can predict the other is correlation. Correlation refers to a statistical measure that expresses the extent to which two variables are related to one another. This relationship can be positive, negative, or zero, indicating how changes in one variable might be associated with changes in another.

In a correlation, the focus is on the degree of association without implying that one variable causes the changes in the other. It's important to recognize that correlation can be quantified using correlation coefficients, which range from -1 to +1, where values near +1 indicate a strong positive relationship, values near -1 indicate a strong negative relationship, and values around 0 indicate no correlation.

Causation, on the other hand, implies that one variable directly affects the other, which is not established merely through correlation alone. Random assignment pertains to experimental research methods, not the relationship between variables, and regression is a statistical method used to predict the value of one variable based on the value of another, which often builds upon the concept of correlation.