Illustration of the change point bias toward blocks with lower count rate. The two count rates, 3 and 2/3, are shown as the blue line, with events placed according to a Poisson process shown as circles. The half-way point between the two terminal photons is shown as a solid vertical line, while the change point placed according to Eq. (3)is shown as a vertical dotted line. It is clear that the half-way change point method is biased towards blocks with lower count rate, but that the adjusted change point location gives a better estimate of the true location of the change point.