The need to improve the quality of care is well recognised. Yet accomplishing this is complicated, messy, and uncertain, requiring that researchers tackle technical (science) and adaptive (emotional, social, cultural, and political) challenges.1 Tension exists between those who say “just do something” to improve quality and those who say “science should be the guide.”2

The two linked studies (doi:10.1136/bmj.d195; doi:10.1136/bmj.d199) suggest that more science is needed. Benning and colleagues evaluated a large patient safety programme (the Safer Patients Initiative; SPI) in the United Kingdom, led by the Institute for Healthcare Improvement.3 4 The Health Foundation initiated and supported the initiative and, laudably, an independent evaluation, grounded in theory and conducted by experts in epidemiology, biostatistics, medical sociology, health services research, and clinical medicine. They performed a quantitative and qualitative evaluation at organisational and patient levels. The evaluation included five substudies that looked at whether the interventions worked and why. In addition to using a rigorous research design, the authors conducted a state of the art analysis, which included using different approaches to evaluate changes over time in treatment and comparison hospitals. This evaluation will serve as a model for the field. It required, however, an interdisciplinary team of experts and appropriate research funding, both of which are rare …