Variable construction was completed using SAS [23] and SPSS [24]. All inferential analyses were conducted in Stata [25]. We estimated both exposure to DSM-IV qualifying traumas and lifetime conditional risk of PTSD among those reporting trauma, stratifying by gender within each tribe. Employing Stata's “svy: tab” procedure, with Pearson χ2 values corrected for survey design and converted to F values, we determined significant differences across groups. Post-hoc analyses of non-overlapping confidence intervals permitted for specific group contrasts; in light of multiple comparisons, we only discuss comparisons significant at p < .01. The percentages of PTSD cases due to specific qualifying trauma categories and events were calculated and contrasted across gender using parallel methods. Logistic regression methods were used to estimate bivariate and multivariate associations of lifetime PTSD with trauma type and demographic variables. Since witnessed trauma exhibited the weakest conditional risk of PTSD, it was selected as primary referent. We assessed interactions among gender, tribe, and worst trauma type; only the interaction between tribe and non-interpersonal events was significant. Adjusted odds ratios are reported separately for this interaction.
