  We have re-analyzed the world data on inclusive polarized DIS, in both NLO
and LO QCD, including the very precise JLab Hall A neutron data, and have
studied the role of positivity constraints, and demonstrated their importance,
in determining the strange and gluon densities. We have shown that higher twist
corrections are essential in the analysis of the present data on the structure
function g1. A consistent QCD analysis is achieved, and results for the
polarized parton densities are given in both the MSbare and JET schemes.
