Waiting time distributions and fitting results. The two panels depict the cumulative distributions of waiting time for Sample I and Sample II, which have been fit with an exponential (Eq. (1)) and a threshold power law (Eq. (3)). The solid lines represent the best-fitting results for each function, while the regions between the two dash-dotted lines indicate the 95% confidence level for each. Additionally, the dashed lines correspond to the thresholded values, x₀, for the threshold power law.