NXS as a function of the light curve duration in the rest frame, Δt_rest. Black dots represent individual NXS values. Blue circles are ensemble averages in bins of Δt_rest. The solid blue line shows a linear least-squares fit to the logarithms of the binned values with slope a = 0.196 ± 0.040. The Pearson correlation coefficient is r = 0.84, with null probability P( >| r | ) = 0.008.