What is the term for a relationship where a change in one variable relates to a change in another?

The term that best describes a relationship where a change in one variable is associated with a change in another variable is correlation. Correlation signifies a statistical association between two variables, indicating that when one variable changes, the other tends to change as well, although this does not imply that one necessarily causes the other.

Understanding correlation is foundational in research because it allows sociologists and other social scientists to identify potential relationships and explore patterns within data. Importantly, while correlation can highlight interesting connections, it is crucial to remember that it does not establish a cause-and-effect link—that's what causation refers to. Causation requires evidence that changes in one variable directly produce changes in another.

Development, on the other hand, typically refers to the processes of change and growth within societal or individual patterns rather than a direct connection between two variables. Thus, correlation is the most applicable term for a relationship of mutual variability between two measured entities.