  To measure the characteristics of quark and gluon jets in hadron-hadron
collisions, two samples of jets are used. Given the large statistics of jets at
the LHC, the two-sample method requires taking into account the following
corrections: (1) use of measured fractions of quark and gluon jets instead of
the model ones, (2) amendment for the contribution of jets with an unidentified
flavour, (3) taking into account the dependence of the distributions of quark
and gluon jets on the conditions for jet sample selections. The paper presents
an improved two-sample method that takes into account these corrections.
