1. A computer-based method for establishing a safety assessment of a process industry plant including multiple organizational units, the method comprising: storing scores in a memory of a computer, each score being related to one of an inspection, undertaken in one of the organizational units with regards to one of multiple defined aspects of the plant, and an answer, given by a human representative of one of the organizational units in response to one of a set of defined questions, each question being related to one of the multiple defined aspects; assigning in the computer each of the scores to the respective one of the organizational units and to the respective one of the aspects, the scores being assigned based on a range including a best case score indicative of proactive safety management, intermediate level scores, and a worst case score indicative of an absence of basic requirements; calculating, in the computer using a processor, aspect-specific scores for each one of the organizational units from the scores assigned to the respective one of the organizational units and to the respective one of the aspects, the calculated aspect-specific scores for an organizational unit having only intermediate level and best case scores being calculated based on a combination of the assigned scores, and for an organizational unit having at least one worst case score assigned to an aspect, the worst case score for that aspect is assigned as the aspect-specific score for that organizational unit; calculating, by the computer, total aspect-specific scores for the plant based on the calculated aspect-specific scores for each of the organizational units; and establishing the safety assessment from the total aspect-specific scores for the plant.