  Within five different approaches to parton propagation and energy loss in
dense matter, a phenomenological study of experimental data on suppression of
large $p_T$ single inclusive hadrons in heavy-ion collisions at both RHIC and
LHC was carried out. The evolution of bulk medium used in the study for parton
propagation was given by 2+1D or 3+1D hydrodynamic models which are also
constrained by experimental data on bulk hadron spectra. Values for the jet
transport parameter $\hat q$ at the center of the most central heavy-ion
collisions are extracted or calculated within each model, with parameters for
the medium properties that are constrained by experimental data on the hadron
suppression factor $R_{AA}$. For a quark with initial energy of 10 GeV we find
that $\hat q\approx 1.2 \pm 0.3$ GeV$^2$/fm at an initial time $\tau_0=0.6$
fm/$c$ in Au+Au collisions at $\sqrt{s}=200$ GeV/n and $\hat q\approx 1.9 \pm
0.7 $ GeV$^2$/fm in Pb+Pb collisions at $\sqrt{s}=2.76 $ TeV/n. Compared to
earlier studies, these represent significant convergence on values of the
extracted jet transport parameter, reflecting recent advances in theory and the
availability of new experiment data from the LHC.
