Table 2.

Levels of System Design

AUTHORS	SYSTEM FACTORS CONTRIBUTING TO HUMAN ERROR
Rasmussen (2000): levels of a complex socio-technical system	Work Staff Management Company Regulators/associations Government
Moray (1994): hierarchical systems approach that includes several layers	Physical device Physical ergonomics Individual behavior Team and group behavior Organizational and management behavior Legal and regulatory rules Societal and cultural pressures
Johnson (2002): four levels of causal factors that can contribute to human error in healthcare	Level 1 factors that influence the behavior of individual clinicians (e.g., poor equipment design, poor ergonomics, technical complexity, multiple competing tasks) Level 2 factors that affect team-based performance (e.g., problems of coordination and communication, acceptance of inappropriate norms, operation of different procedures for the same tasks) Level 3 factors that relate to the management of healthcare applications (e.g., poor safety culture, inadequate resource allocation, inadequate staffing, inadequate risk assessment and clinical audit) Level 4 factors that involve regulatory and government organizations (e.g., lack of national structures to support clinical information exchange and risk management).
For comparison, levels of factors contribution to quality and safety of patient care
(Berwick, 2002; Institute of Medicine Committee on Quality of Health Care in America, 2001)	Level A – experience of patients and communities Level B – microsystems of care, i.e. the small units of work that actually give the care that the patient experiences Level C – health care organizations Level D – health care environment