The correlations between 2003–2004 average
net income differential and 2010–2011 average
net income differential both when examined in
aggregate and by industry are all positive and
significant, except for that of Industrials. The
significant positive correlation indicates that
sample companies which have higher (or lower)
net income differential continue to have higher
(or lower) net income differential. However, the
results of paired t-tests show that the 2-year
average net income differential at the beginning
of the period studied is not signifi cantly different
from that at the end of the period studied at the
fi ve percent level of confidence when examined
both when examined in aggregate and separately
by industry