The size distributions of precursors (upper panel: differential distributions, lower panel: cumulative distributions). Panels (a)–(d) display the size distributions of peak fluxes (P), durations (D), rise times (t _r ), and decay times (t _d ), respectively. The green solid line is the best fit and the gray region represents the 95% confidence level, and the dotted line is marked as the threshold x ₀.