Interaction of interventions. Whenever more than one intervention is used with the same client, it is difficult or impossible to tell which intervention affected the target. Example: Kevin and Vickki,...

Interaction of interventions. Whenever more than one intervention is used with the same client, it is difficult or impossible to tell which intervention affected the target. Example: Kevin and Vickki, young parents of an abused child, were being aided by a series of parent skills training classes, followed by assertiveness training, and later by social effectiveness skills training. Communication between them seemed to have improved, and they were caring for their daughter more consistently. But at the end of intervention, the counselor wasn’t able to pinpoint which of these treatments was most useful.