Sociology Plus
Concomitant Variation Definition
Concomitant variation is an empirical relationship between two variables in which the magnitude of one rises or falls in proportion with the magnitude of the other. The relationship is actual rather than merely logical: heating a metal strip, for instance, produces a concomitant variation between temperature and length.
Use in Causal Reasoning
Observed concomitance is a starting point for causal inference. If we persistently find that as people grow richer they more frequently vote for a right-wing party, we have concomitant variation and may begin to consider whether the first change causes the second. Where the relationship holds across all values of the variables, it is called constant concomitance. The correlation between variables can thus serve as a test of causal hypotheses — the method by which Émile Durkheim tested the principal causal claims of Suicide (1897), and a cornerstone of the comparative method.
Limits in Social Science
Compared with the natural sciences, the social sciences very rarely uncover relationships of constant concomitance, which constrains how firmly causal conclusions can be drawn from correlational evidence.