The relative validity of inferences about mediation as a function of research design characteristics

Tests of assumed mediation models are common in the organizational sciences. However, the validity of inferences about mediation is a function of experimental design and the setting of a study. Regrettably, most tests of mediation have relied on the application of so-called "causal modeling" techniques to data from nonexperimental studies. As we demonstrate, inferences about the validity of assumed mediation models are highly suspect when they are based on the findings of nonexperimental research. One of the many reasons for this is the failure of the model being tested to be consistent with reality. Valid research-based inferences about mediation are possible. However, inferences from such tests are most likely to be valid when they are based on research that uses randomized experimental designs. Strategies for conducting research using these and other designs are described. Finally, we offer a set of conclusions and recommendations that stem from our analysis.