Fig 4. The comparison of the overestimate (5) and (6) and original model (3) and (4) by considering the implementation of biannual MDA with ϵ = 0.4 and ω = 0.5 and varying k and R₀ values.

(a) R₀ = 2, k = 0.05, n > 5.83 and MSE = 0.1258 × 10⁻⁴. (b) R₀ = 2, k = 0.5, n > 8.34 and MSE = 0.2167 × 10⁻². (c) R₀ = 1.8, k = 0.05, n > 2.86 and MSE = 0.5217 × 10⁻⁶. (d) R₀ = 1.8, k = 0.5, n > 5.38 and MSE = 0.6392 × 10⁻³.