Summary: KS-test tests whether two samples are drawn from the same distribution. It returns two floats: the first is KS statistic, the second is two-tailed p-value. In terms of the Null hypothesis, if the K-S statistic is small or the p-value is high, then we cannot reject the hypothesis that the distributions of the two samples are the same. Applying to the Vision Zero case, since the p-value is orders of magnitude less than the critical value 0.01, we reject the Null hypothesis that there is no statistical difference in the for the before and after the adoption of Vision Zero.  Based on the daily probabilities of the cumulative number of Accidents  before and after the adoption of Vision Zero Adoption.