is exp(β11)/exp(β31), which is conventionally called a relative risk ratio (RRR) or odds ratio (although neither term is strictly accurate). The assumption that predispositions have a stronger influence on the risk of PTSD when events are less severe can be expressed mathematically by 0 < β11 < β31. If the results point in the opposite direction or if the two coefficients are equal, then the assumption, as stated above, is rejected.
