From top left to bottom right: (a) P–P plot for ~2000 simulations with only chromatic noise, injected at much lower than 1/T_span; (b) the confidence interval of the recovered achromatic amplitude for various levels of injected red noise slope for the simulations is shown in (a); (c) P–P plot for ~1000 simulations with only chromatic noise periodic on 1/T_span; (d) P–P plot for ~1000 simulations with chromatic, achromatic and scattering variations, periodic on 1/T_span.