Mean ($\langle N_{\rm ch} \rangle$), standard deviation ($\sigma_{\rm ch}$), and scaled variance ($\omega_{\rm ch}$) of charged-particle multiplicity distributions as a function of the number of participating nucleons for experimental data along withHIJING and AMPT (string melting) models for Pb--Pb collisions at \snn~$=$~2.76~TeV, shown in panels (a), (b), and (c), respectively. For panel (a), $\langle N_{\rm part} \rangle$ for the two models are shifted for better visibility The statistical uncertainties are smaller than the size of the markers. The systematic uncertainties are presented as filled boxes.