A method of classifying hadron jets is presented which uses the $z$ correlations of all hard particles in the jet. We show that this leads to cuts which will allow preparation of "quark-enhanced" samples of jets. Such samples should be useful for computing the $W$ mass in jet-jet invariant-mass distributions, and in searches for new particles which decay predominantly into jets. We urge experiments with $e^{+}{e}^{-}$ data to test these theoretical predictions by comparisons of their "quark-enhanced" and "gluon-enhanced" jet samples.

• Received 12 January 1990

DOI:https://doi.org/10.1103/PhysRevD.42.811