Histograms of the significance of on-pulses (gray hatched step) and off-pulses (blue no hatched step) for PSR J0908−1739 taken on 23 May 2016. The upper plots are for statistics of single pulses, and the lower plots are for subintegrations of every 32 pulses. The distribution of the off-pulse significance can be modeled with a normal function with a mean of zero and a standard deviation of σ_off. The normal function is scaled with f_n and represented by a red dotted line; it is subtracted from the distribution of on-pulse significance with the residuals indicated by black “plus” symbols in the panel. The residual distribution is modeled by a lognormal function with a mean of μ_on and a standard deviation of σ_on. Green solid, dash-dotted, and dashed lines are for the modeled distribution, the mean, and the lower three-sigma limit.