Effectiveness, Quality & Performance

Thomas McLellan, PhD

October 2010

Dr. Thomas McLellan, Director at the Center on Substance Abuse Solutions at the University of Pennsylvania, describes the difference between three commonly misused terms: effectiveness, performance, and quality. He argues that effectiveness is about outcomes while performance is about functioning, and good treatments without follow-up might be misunderstood as poor treatments rather than incomplete treatments. He provides two compelling examples of such a misunderstanding.