NPV Robustness Functions.

The sensitivity, σ, and the specificity, ψ, each take the value 0.9. The estimated prevalence, π~, is 0.15, and the estimated error of π~ is w_s=π~/3. The expert estimate of the negative predictive value, NPV, is denoted NPV_e. The acceptable error of this estimate is ɛ.

σ=ψ=0.9, π~=0.15, w_s=π~/3.