Monte Carlo experiment on HiCAT for segment tolerances obtained from the simulated PASTIS matrix diagonal using Eq. (12). The target contrast, Δc_t = 10⁻⁶, as determined by the simulated tolerances, is indicated with the dashed black line. The experimental mean over 1000 segmented WFE maps (dashed-dotted red line) does not recover the target contrast. However, we are able to predict this discrepancy analytically: Using Eqs. (8) and (9), we can calculate the resulting contrast mean (dashed-dotted orange line) and variance (dotted orange lines) from the experimental PASTIS matrix and simulated segment tolerances directly. For details, see the main text.