Fig. 4

Optimal sampling designs with prevalence accuracy as a function of costs. Accuracy (relative root mean square error) of prevalence (Ψ) as a function of costs (USD) using arbitrary cost constraint (dotted vertical line) of $7500 USD for a) a subset of the simulation scenarios with the true test sensitivity of 0.3 and 50% of the initially sampled population with repeat tests; b) a subset of the simulation scenarios with the true test sensitivity of 0.3, true population infection rate (true prevalence) of 1, and 100% of the initially sampled population with repeat tests. Optimal designs are indicated within the figures with arrows