Commentary: Establishing Causality in Quality Improvement Studies.

In this Pediatrics Quality and Safety issue, Moorthy et al describe a quality improvement project to improve pediatric sepsis care in their pediatric emergency department (ED) (Causal Association of Physician-in-Triage with Improved Pediatric Sepsis Care: a Singlecenter, Emergency Department Experience). Their approach begins traditionally for an improvement project, collecting baseline data for their key measures for the previous 4 years. However, their plans changed when they noted special cause variation in the fall of 2018. As a result, they quickly pivoted their approach to learning from this special cause. Thus, their article is about this special cause. Shewhart theory of common and special cause variation forms the cornerstone of the Science of Improvement.1 The analysis of baseline data using statistical process control directs our improvement work in 1 of 2 directions2: