Which element is NOT a criterion for establishing causality?

To establish a causal relationship in research, certain criteria must be met. The correct answer indicates that "omitted variables" is not a criterion for causality, which highlights a fundamental aspect of how researchers evaluate causal claims.

Causality typically requires an association between the variables (there must be a correlation or relationship), a proper time order (the cause must precede the effect in time), and nonspuriousness (the relationship must not be due to some other variable that influences both the cause and the effect). Omitted variables, however, refer to potential confounding factors that have not been accounted for in the analysis. While failing to control for omitted variables can affect the validity of a causal inference, the presence of omitted variables themselves is not a formal criterion for establishing causality.

In summary, establishing causality relies on the criteria of association, time order, and nonspuriousness, whereas omitted variables represent a potential pitfall or challenge in the research process rather than an established criterion. Therefore, identifying omitted variables as not being a criterion reflects an understanding of the foundational elements required for causal inference.