“…Other writers have provided guidelines to assist the professional in determining causality. Parlour and Jones (1980) suggest that various sources of information, including extended interviews with the claimant, family and friends, prior physicians, employers, and other associates; review of medical, military, scholastic, and employment records; observation of the claimant outside the office setting; and results from a trial of treatment be considered when developing a theory as to causality. Leavitt (1980), in turn, recommends that the following factors be evaluated in arriving at an opinion as to causality: (1) workplace stressors, including concurrent interpersonal employment context, preparedness for trauma, job performance requirements, and epidemiological considerations; (2) 'linkage events' that can be assumed to mediate between the occurrence of the stressor and the disabling condition, such as emotional or psychophysiological reactions to the stressor, as well as psychological mechanisms that can be proposed to account for the clinical condition; and (3) susceptibility to the workplace stressor, in terms of past history or psychological mechanisms.…”