p values of KS goodness-of-fit tests comparing Von Mises cumulative distribution function (CDF) models to the empirical phase CDFs, shown for each frequency bin of FRB 20121102A (top) and FRB 20180916B (bottom). For each frequency bin, the p value quantifies whether the observed burst phase distribution is consistent with a Von Mises model. The dashed horizontal line marks the 3σ rejection threshold (p = 2.7 × 10⁻³); values below this line indicate that the Von Mises model is statistically rejected. The inset highlights the p values in the lowest-frequency bins for FRB 20121102A.