Indigenous Diviner Diagnostic Consensus and Psychiatric Referral Concordance in Zimbabwean Shona Communities: A Factorial Vignette Estimation of Etiological Agreement and Care Pathway

Diviner diagnostic reasoning in Shona communities is often treated as a unitary traditional practice, yet its internal structure and its relationship to biomedical referral remain poorly specified. The design parameters were eight, sixteen, twenty-four and thirty-two clusters; effect sizes of three, five and eight percentage points; and two thousand replications per design cell. The intraclass correlation was 0.64, the between-cluster standard deviation was 6.0, and the residual standard deviation was 4.5. Power estimation indicated that fifty-two clusters were required to detect a five-percentage-point effect at eighty per cent power. The analysis specifies how etiological agreement and referral concordance can be estimated with known precision, identifies the cluster counts at which the design becomes informative, and establishes the boundary conditions under which diviner-psychiatrist concordance can be distinguished from chance. The contribution is a design framework for studying diagnostic consensus in indigenous healing systems, not a report of observed diviner behaviour.