The tree of causes is a methodology implemented for the Investigation of Work Accidents. The method of the tree of causes is based on Systems Theory, which addresses the accident at work as a complex phenomenon. In this way the methodology studies several possible causes and thus reveals the variations and deviations that occurred in the activity. The application of the cause tree methodology requires detailed reconstruction and as accurately as possible the history of an accident. Only the facts should be recorded , also called causes of accidents. Mainly, because above all the analysis of the facts must be carried out without judgment of values or interpretations. From the injury suffered by the victim, the network of causes that led to the work accident is identified. variation concept. The variation is the change that occurred in relation to the normal functioning of the work system, that is, without accidents. Thus, the identification of variations is considered indispensable for the purpose of identifying the real cause of the accident. the cause tree must finally point out all the failures that preceded the final event (injury or not), thus facilitating the adoption of control measures. Doubts? Leave us a message!