Patient safety systems use redundancy (double checking) procedures to minimize errors and prevent adverse and near-miss clinical events. However, redundancy and back-up procedures alone do not guarantee that patient morbidity and mortality will be reduced. In fact, patient safety literature now identifies the human factor as an essential element in outcomes. The human factor includes personal issues, task-oriented issues and interactions among staff. Most literature on patient safety calls for cultural changes in health care systems to minimize the human factor.