It makes a difference as to who’s behaviour you are interpreting.

For a worker you need to look at his or her actions and specifically the intention of the actions. Find out the background on training, proficiency, knowledge of procedures and experience as well as the environment, applicable procedures, system support and circumstances.

For interpretation at managerial level you will need to focus on resolution of deficiencies in safety defences. How well was the team managed? Did an error happen before and what did the manager do about it then?