Distribution of the frequency and amplitude deviations for the two main pulsation modes of V391 Peg. The deviations, in units of 1σ errors, are the differences between the values obtained from the original light curve and those obtained from 1000 artificial light curves created by the MC simulator of Period04 (Lenz & Breger 2005). The synthetic light curves are built using the five p-modes of Table 3 and adding Gaussian noise at the same level as the original data. The 2D distributions are also projected into 1D histograms and compared with a normal distribution (red).