When comparing the unique environmental estimate as a function of assessment method, excluding the Kaij outlier study, there was no significant heterogeneity in the parameter estimates (χ2 = 0.27, df = 1, p = 0.60). Follow-up tests were conducted to test for heterogeneity within each assessment group. Significant heterogeneity was found for studies using interview-based assessments (χ2 = 24.68, df = 14, p = 0.04), but not for record-based assessments (χ2 = 7.08, df = 4, p = 0.13). Taken in concert with the previous findings, the heterogeneity within the interview-based assessment method is primarily a function of heterogeneity in the male unique environmental parameters.
