COVER STORY financially successful future. It will be apparent that the key differentiator between cost accounting and the other two uses of the "Cost Mea- surement" box is that cost accounting is deeply con strained by regulatory practices and by describing the past in accordance with principles of financial account- ing. The other two categories offer diagnostic support to interpret and draw inferences from what has already taken place and what can happen in the future. Cost reporting and analysis is about explanation. Decision support with cost planning is about possibilities. The message at the bottom of the figure is that the value-add, utility, and usefulness of the information increase, arguably at an exponential rate, from the left side to the right side of the diagram. 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 under- stand the impact that changes will have on future ex penses, so the focus shifts to resources and their capacities. 1 This involves classifying the behavior of resource expenses as sunk, fixed, step-fixed, semivariable, variable, and dis- cretionary 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 individ ual resource expense depends on both the planning time horizon and the ease or difficulty of adjusting the individ- ual resource's capacity (its "stickability"). This wanders into the messy area of marginal incremental cost analysis that textbooks oversimplify but that is complicated to cal- culate accurately in the real world. Figure 5 illustrates how a company's view of its profit and expense structure changes as analysis shifts from the