Number of jet splittings until the splitting selected by grooming method in PYTHIA8 Monash 2013 at $\sqrt{s}=5.02$ TeV. This figure is for R=0.4 jets found at particle level. The grooming methods that are compared are leading kt, leading kt with z > 0.2, dynamical kt (a=1), and dynamical time (a=2). Each grooming method selects a different population of splittings. If no splitting was selected, it is recorded in the 0 bin. The z > 0.2 method tends towards high n because this counts all possible splittings (even those which don't pass the z > 0.2 cut). Note that this is _not_ equivalent to $n_{\mathrm{SD}}$.

The different grooming select different splittings based on their intrinsic grooming characteristics.