Top panel: probability plot comparing the binned out-of-trail CCF values to a sampling of the normal distribution (black rings). The dashed cyan line is the calculated linear regression. That the correlation so closely follows a linear trend indicates the out-of-trail values are well described by a Gaussian out to ± 4σ . Bottom panel: histogram of the binned in- (dotted line) and out-of-trail (solid line) CCF values. Error bars were calculated as the square root of the individual bin count, normalized by the sample size. A two-sided Welch’s t-test gives a 4.3σ rejection of the null hypothesis that both populations are draw from the same distribution.