Distributions from ensemble tests conducted on the Pythia ttbar MC
samples generated with (mt,mtb)=(170,165)GeV consisting of 1000 pseudo
experiments with data-like composition (Pythia ttbar with  + Alpgen
W+jets).  The histograms from left to right are: (a) expected
uncertainty of the extracted average mass, (b) extracted average mass
(c) pull for the extracted average mass. Only the distributions for the
e+jets channel are shown.