ON THE USE OF CAUSAL CRITERIA

Background. Two recent accounts of the use of causal criteria make opp osite claims: that criteria should be used more often to avoid bias in assessments of weak associations and, in direct contrast, that criter ia are scientifically invalid. Methods. A recent review of the current practice of causal inference in epidemiology, as well as some more th eoretical concerns, reveals errors in the two claims. Results. In prac tice, epidemiologists often use the criteria of consistency, strength, dose-response, and biological plausibility, but not often temporality , when judging weak associations. These criteria are used for causal a ssessments as well as for making public health recommendations. In the ory, causal criteria can be used to either refute or predict causal ef fects. Conclusion. Research on causal inference methodology should be encouraged, including research on underlying theory, methodology, and additional systematic descriptions of how causal inference is practise d. Specific research questions include: to what extent can consensus b e achieved on definitions and accompanying rules of inference for crit eria, the relationship of meta-analysis to the criterion of consistenc y, and the interrelationships of criteria such as consistency, strengt h of association, and biological plausibility.