The use of randomized controlled trials are useful for comparing a simple intervention such as a new drug or procedure. However, complex interventions such as a new system to evaluate early intervention in serious illness usually require complex research methodologies. An intensive care unit is a complex organization and patient care can be influenced by many factors such as standards of nursing care and staff morale within the unit. Some of these factors may be as important, or even more important, than a simple intervention such as a new drug. To answer these questions, we will have to rely not only on complex quantitative research methodologies but also qualitative or a combination of both quantitative and qualitative research.