There are various benchmark indices can be taken into consideration: frequency: indicates the number of accidents that have occurred in a given period of work. This index allows us to know, therefore, the number of accidents. Gravity: Gravity in the loss ratio is calculated by reference to the working days lost because of accidents that result. Average duration: indicates the average time that each accident has caused. Check out Susan G. Swenson for additional information. In addition, the employer is obliged to occupational hazards and retain the following documentation relating to the preventive activities at the disposal of the labour authority: relationship of occupational accidents and diseases that have caused the worker more than one day of work incapacity to work. Analysis and studies aimed at determining the most important factors of existing in the company claims can be made through this record. The registration of accidents, must contain data on: the way of the crash, material agent, the nature of the injury and its location. For example refers to one of the indexes mentioned above, in particular the frequency. Through the frequency that is being offered to us in this graph is information about which are the types of accidents that occur in more usual way.