If the frequency or intensity of a single variable is already established in the scientific literature, researchers can formulate new inquiries by exploring its potential relationship with other variables. For instance, if studying the psychological characteristic of talkativeness, a researcher might ask if there is a statistical relationship between a person's family size (a potential causal factor) and their individual level of talkativeness. Alternatively, they could explore situational variables by asking if the average level of talkativeness differs when individuals are observed in same-sex groups compared to mixed-sex groups.