The reason for differentiating between fixed and variable so emphatically is because variable cost
spending requires no decision; it is dictated by volume.
Fixed costs, on the other hand, require a
management judgment and decision to increase or decrease the spending.
Sugar is an example of a
pure variable cost. Each change in volume will automatically bring a change in the sugar cost; only the
yield can be controlled. Route salesmen's salaries would be an example of a fixed cost that is fairly
sensitive to volume, but not pure variable. As volume changes, pressure will be felt to increase or
decrease this expense, but management must make the decision; the change in cost level is not
automatic. Depreciation charges for plant would be an example of a relatively extreme fixed cost. Very
large increases in volume can usually be realized before this type of cost is pressured to change.