CONCEPTUAL FRAMEWORK
We believe that most medical errors result from numerous latent errors that exist within complicated systems of care delivery as opposed to only the errors of individuals. This systems approach to medical error is well supported and consistent with healthcare's historical approach to quality improvement as shown in the following figure.

Medical errors can be caused by factors at different levels of a system. At level 1, individual thought processes may trigger errors. However, an individual who triggers an error at the "sharp end" may not be the root cause of that error. Instead, it may be related to the interactions of individuals with inadequately designed medical devices. (level 2). Factors related to the functioning of teams may also lead to errors (Level 3), as may organizational policies and structures (e.g. resource allocation, staffing and scheduling, training) (level 4). Finally, societal laws and regulations influence all the other levels and may affect the frequency and types of errors.