Activity Analysis, Cost Behavior, and Cost Estimation
Cost Behavior Patterns
: Understanding cost behavior
patterns is important to managers as they plan, control, and make
decisions in the operation of their organizations. (e.g., a manager
must understand how costs behave across various levels of activity before a
budget can be prepared.)
Constant on units, fluctuate on total
: Variable costs are costs
that remain constant on a per-unit basis and fluctuate in total in direct
response to changes in the cost driver. (e.g., the paper costing in
giving exams varies with the number of students in a class).
Increase in steps
: Step-variable costsare nearly
variable, but such costs increase in small steps rather than in direct
proportion to change in the cost driver. (e.g., if a class is a bit
larger than usual, an additional exam proctor may have to be hired. This
increase in part-time hourly help increases by a step as the number of
students in the class grows.
Constant in total but fluctuate individually
: Fixed costs stay
constant in total but fluctuate on a per-unit basis across the ranges of
: Professorsí salaries are fixed, and more students
enrolling in the individual courses will not affect the salaries. The salary
cost per student will, however, fluctuate depending on the number of
students in each class.
Fixed over a wide range
: Step-fixed costs are fixed within a
wide range of activity but will change outside the range.
: If a course increases by a large number of students, it
will be necessary to add another section and hire another instructor. The
fixed cost then jumps to another step.
Change in response to cost driver
: A semivariable cost (mixed
cost) is one that changes in response to a change in a cost driver, but
not in direct proportion. Such costs have both variable and fixed elements.
: A printerís fee for brochures, which includes a fixed
set-up cost per page and a per-copy (i.e., variable) charge for
running the total copies needed.
Represented by a curve
: A curvilinear cost function cannot be
represented with a straight line but instead is represented with a curve
that reflects either increasing or decreasing marginal costs.
Range which manager expect
: The relevant range is the range
of activity within which managers expect a company to operate and within
which managers can predict cost behavior with some certainty. Within the
relevant range, even curvilinear costs may behave in a linear fashion.
COST CATEGORIES AND STRUCTURES
Definite physical relationship to cost drivers
: An engineered
cost is one that bears a definite physical relationship to the cost
: The food cost of a restaurant, as it is impossible to serve
more meals without incurring more food costs.
Committed costs continue
: Managers must distinguish between committed
costs and discretionarycosts. Committed costs will
continue even if an organization shuts down for a short time (e.g.,
the cost of facilities and top management). These costs cannot be eliminated
without endangering an organizationís overall health and existence.
Result from decisions
: Discretionary costs exist as a result
of a management decision (for example, a training program, an advertising
campaign, corporate contributions, and so forth). In comparison with
committed costs, such costs are more easily changed in bad economic time
without doing serious long-run harm to the entity.
Automation and labor union cause more fixed costs
: Fixed costs are
becoming more prevalent in many industries because of automation and labor
unionsí success in negotiating for a stable workforce. Costs that were
once variable are becoming fixed, which makes a company less able to respond
rapidly to changing economic conditions.
Cost Estimation Methods
uses account information and judgment: The account-classification
method (also called account analysis) requires a study of an account in
the general ledger. The experienced analysts use the account information as
well as their own judgment to determine how costs will behave in the future.
Visual-fit uses graphing
: With the visual-fit method, an
analyst examines a cost by plotting points on a graph (called a scatter
diagram) and places a line through the points to yield a cost function.
This method is more objective than the account-classification method, but it
is still lacking because two cost analysts could (and likely would) visually
fit different lines. Such an approach is useful, though, because it helps
spot nonrepresentative data points, or outliers.
High-low considers only two points
: The high-low method of
approximating cost behavior considers only two points of data, the highest
and lowest, for activity within the relevant range. The method first focuses
on cost changes, allowing an analyst to determine the presence of any
variable cost. Next, fixed costs are determined by subtracting variable cost
from the total cost at either of the two data points.
Least-squares statistically based
: The least-squares method
is a statistical approach that is both objective and considers all the data
points. By using mathematical formulas to arrive at the best possible cost
line (i.e., the regression line), it is more accurate than the
methods mentioned previously. The regression line is in the form Y=a + bX,
where X is the independent variable and Y is the dependent
variable. The coefficient of determination (R2) can be
used to judge the lineís goodness of fit.
Multiple regression statistically based with multiple varaibles
regression is a statistical method that can be used to estimate a cost
function when there is more than one independent variable.
: The fuel cost for an airline is determined by the number of
miles flown and by other variables such as wind speed and load.
Data Collection Problems
: The process of collecting appropriate data to use in
any cost-estimation method is very important. The best method will yield
worthless predictions if it is based upon poor data. Common pitfalls to
avoid are listed of page 262 of the test and include such items as missing
data, outliers, mismatched time periods, inflation and other factors.
No historical data
: The previously mentioned of cost estimation assume
that there is a historical pool of data to based your decisions upon. In new
environments without such a pool, the engineering method of estimation
may be used. Instead of beginning with past cost, the engineering method
begins by asking how much a product should cost given design specs and
manufacturing techniques. (e.g., the industrial engineers time and
Cost Behavior Issues
More experiences labor is more efficient
: A learning curve
expresses the relationship between labor time and output. As the labor force
becomes more experienced with a new process, workers become more efficient
and the cost per units falls. This phenomenon is considered in the
prediction of costs, particularly the cost of new products.
Simplify assumptions to reduce costs
: All cost-estimation methods are
based on simplyfying assumptions so that the benefits of use outweigh the
costs of data collection and manipulation. These assumptions include: cost
behavior depends on one activity variable (except for the
multiple-regression method), and cost behavior is linear over the relevant
Work measures facilitates cost estimation
: Cost estimation is
facilitated by a technique known as work measurement, which is often
used in nonmanufacturing enviroments. Work is divided into indivdual
activities, or control factor units, and costs are accumulated for each
: The U.S. Postal Service would consider the sorting of mail
as an activity and would measure this activity in terms of the number of