Distribution of SDSS light-curve statistics in g and z bands. The statistics shown are (from left to right) minimum time separation between any two observations in a light curve (﹩\mathrm{Min}\,{\rm{\Delta }}t﹩), the maximum time separation between any two observations in a light curve (﹩\mathrm{Max}\,{\rm{\Delta }}t﹩), number of epochs in a light curve, and the median photometric error for observations in a light curve.