Distribution of α_out − α for the noise-free case. It is centered at ⟨α_out − α⟩ =  −0.056 with a width of σ(α − α_out) = 0.098. Comparing this plot with Fig. 4 shows that the total amount of DR is underestimated by 8.8% because α_in ≤ α by definition. The detections where α < 0.06 are overplotted in red. Clearly, in these cases the detection of DR is difficult. In most cases, α_out > α which demonstrates the limits of our method.