Estimates of the mean recency duration, ω, under both the simultaneous estimation of ω and α, and when assuming α = 0%, for T = 1 year, are compared to published estimates (by ‘back-calculation’ in the repeat donor population [27] and using seroconversion panels [18], [27]) as a function of test threshold. The minimum and maximum ω occurring in the 95% confidence regions (CRs) for ω and α (simultaneous estimation), as well as 95% confidence interval (CI) limits for ω (assuming α = 0%, with no uncertainty) are also displayed. Estimates shown in Part A pertain to the South African population, while those in Part B pertain to the USA population.