What does correlation or association refer to in the context of research?

Correlation or association in the context of research refers to the simultaneous variation in two variables. This means that when one variable changes, there tends to be a corresponding change in another variable. The relationship can be positive, where both variables increase or decrease together, or negative, where one variable increases while the other decreases. Correlation does not imply causation; it merely indicates that a relationship exists between the two variables being studied. This foundational understanding is crucial in research, as it sets the stage for further investigation into possible causal relationships, distinguishing correlation from direct causation.