- Accident investigations help determine what happened, find ways to prevent recurrences, control claims, and save money for the firm. Supervisors should investigate to learn job details, assist training, and be responsible for procedures. - Keys to a successful investigation include being prepared, starting as soon as possible, and investigating all near misses, which are incidents that could have caused injury. - Immediate causes include unsafe acts like speeding or horseplay, and unsafe conditions like defective equipment or poor housekeeping.