When the cost reporting and analysis component shifts
right to the decision support with cost planning box in
Figure 4, analysis shifts to the realm of decision support
via economic analysis. For example, we need to understand
the impact that changes will have on future expenses,
so the focus shifts to resources and their capacities.
This involves classifying the behavior of resource expenses
as sunk, fixed, step-fixed, semivariable, variable, and discretionary
with changes in service offerings, volumes, mix,
processes, and the like. The classification is tricky. Here’s a
key concept: The “adjustability of capacity” of any individual
resource expense depends on both the planning time
horizon and the ease or difficulty of adjusting the individual
resource’s capacity (its “stickability”). This wanders
into the messy area of marginal/incremental cost analysis
that textbooks oversimplify but that is complicated to calculate
accurately in the real world.