Different approaches examine the connection between operational events and psychological consequences. Much of the current research that analyzes the effects of operational stressors has focused on how the symptoms of psychological distress grow as the number of stressors experienced increases. Some studies have examined the effects of specific stressors on psychopathological symptoms and problematic behaviors. Some of these stressors include killing others, being exposed to atrocities, working with human remains, and being injured. There are further associations between categories of stressors and psychological outcomes using scales that measure the frequency and severity of stressors during deployments. It was found that working in dangerous environments and being exposed to death led to PTSD and MDD. Analyzing the types of stressors can allow for preventative interventions to be created so that military personnel can effectively handle the situations and stress brought along with them.