  We review the overlap pathology of the Glasgow reweighting method for finite
density QCD, and discuss the sampling bias that effects the determination of
the ensemble-averaged fugacity polynomial expansion coefficients that form the
Grand Canonical Partition function. The expectation of the difference in free
energies between canonical partition functions generated with different
measures is presented as an indicator of a systematic quark number dependent
biasing in the reweighting approach. The advantages of building up an unbiased
polynomial expansion for the Grand Canonical Partition function through a
series of parallel ensembles generated by reweighting with imaginary chemical
potentials are then contrasted with addressing the overlap pathology through a
secondary reweighting.
