The Illusion of Statistical Control: Control Variable Practice in Management Research

The authors extend previous recommendations for improved control variable (CV) practice in management research by mapping the objectives for using statistical control to recommendations for research practice. Including CVs in research designs to permit statistical control of "nuisance" variance is a common research practice that is subject to well-documented and potentially serious problems. Yet because CVs are frequently weakly related to focal variables, they rarely influence the interpretation of results. As a result, current practice offers an illusion of statistical control when in fact little control actually occurs. The authors extend the growing literature on CV practice by examining the ambiguity of researchers' stated purposes for using statistical control that makes it difficult to determine whether common CV practice accomplishes any of these intents effectively. Guidelines for improving research practice are offered, including adopting a conservative stance toward the inclusion of CVs in the analysis of quasiexperimental and correlational designs guided by the principle "When in doubt, leave them out.".