Mobile Crisis Team Response Latency and Trauma-Related Mental Health Crisis Relapse Among South African Callers: A Target-Trial Emulation of Dispatch Time Thresholds

Trauma-related mental health crises in South Africa are frequently managed through mobile crisis teams, yet the relationship between dispatch latency and relapse remains poorly characterised because randomisation to response delay is infeasible. The design uses between-cluster standard deviation of 6.0, residual standard deviation of 4.5, and intraclass correlation of 0.640. Power was estimated across 2000 replications per design cell for cluster counts of 8, 16, 24 and 32 and effect sizes of 3, 5 and 8 percentage points. The analysis indicates that 56 clusters are required to detect a 5 percentage point effect at 80% power. Minimum detectable effect curves and power curves characterise the trade-off between cluster count and detectable effect. The framework provides a template for evaluating dispatch time thresholds without inventing observational data, and clarifies the conditions under which target-trial emulation can support causal inference about crisis response latency.