LEVELS OF EVIDENCE

Effect size in psychiatric evidence-based practice care

Developing evidence-based practice skills requires a familiarity with the language and terminology of clinical research. Few articles discuss concepts, such as effect size, that must be understood to determine if the findings of studies are clinically meaningful. Clinically meaningful results of studies are determined by the effect size of an intervention. The effect size of an intervention, such as cognitive-behavioral therapy, can be calculated from the findings of different studies using different designs and populations. However, the determination and use of an effect size is important to clinicians using research findings to guide practice.

Evidence-based practice in psychiatric care: defining levels of evidence

Identification and application of the current research evidence to a clinical problem is a goal reflected in professional codes and institutional mission statements. The use of expert opinions and traditions is no longer clinically or legally defensible in an era of using emerging evidence. Application of current research evidence is the emerging standard of care for all health care personnel, including psychiatric mental health care. The emergence of evidence-based practice as the new standard of care obliges all health care providers to use the latest research evidence. The need to make an intervention based on the highest level of evidence mandates that clinicians understand levels of research evidence and how the different classification systems of evidence compare. In this article, the levels of research evidence are reviewed to provide a framework for determining the best evidence to use as a basis for clinical interventions. J Am Psychiatr Nurses Assoc, 2008; 14(3), 181-187. DOI: 10.1177/1078390308321220.