Presuming that
the sustainability KPI is entirely variable, the efficiency
improvement appears to be 10.7% (100% – 89.3%).
Using the same activity variation but factoring out the
fixed portion, which is identical to the approach used in
Table 2, Table 4 shows the more accurate measure of efficiency
improvement of 11.5% (100% – 88.5%). The consequence
of treating the behavior of the sustainability
KPI as entirely variable results in a more conservative
estimate (i.e., underestimating efficiency improvements).