Evaluating the dodo's verdict: Do all interventions have equivalent outcomes?

There is a persistent and widely held belief—referred to as the “tie-score effect” or the “dodo bird verdict”—that different types of intervention have equivalent outcomes. However, the research supporting this belief has been limited largely to comparing methods drawn from different schools of psychotherapy with emphasis on treatment of the emotional problems of adults. A review of relevant meta-analyses published in the past decade (n = 31) was undertaken to determine whether this verdict applied to the broader range of problems and interventions typically found in clinical social work. The majority of these meta-analyses reported differential effects associated with different types of interventions. There proved to be little basis for extending the dodo's verdict to the range of problems and interventions of concern to social workers. Moreover, several patterns of differential effectiveness occurred that could help guide the practitioner's choice of interventions.