Adding an effectiveness dimension to the two behaviour dimensions gives the Tridimensional Leader Effectiveness Model: a style appropriate to its environment, judged by results, is effective and the same style in the wrong environment is ineffective, so any of the four styles can be either. The authors' evidence is Korman's review of more than twenty-five studies (no predictive value of the Ohio State dimensions as situations change), Fiedler's finding that directive and non-directive leaders each succeed under some conditions, and cases such as combat-trained officers whose high-task style failed with research staff on the DEW line. The situational variables to diagnose are the leader, the followers, the boss, key associates, the organization, job demands and decision time; they interact. The effective leader diagnoses the environment and then adapts the style or changes other variables. Style 1 suits a genuine crisis, but treating an organization as if it were in crisis produces one: expectations are self-fulfilling, so the leader should hold positive assumptions about followers' potential.
The graph holds this control, the 0 it maps to, and the evidence behind each claim, over MCP and REST.