Two-dimensional marginalized posterior distributions of log₁₀A_GWB and γ_GWB recovered for the OneF dataset corrupted with 0% (red), 0.3% (blue), 1% (green), 5% (pink) and 10% (orange) of outliers. Each pair of distributions (log₁₀A_GW; γ_GW) has been recovered separately and then overlapped to be easily compared. The black lines and the square indicate the injected values of the amplitude and spectral index.