Cost Drivers
Production Example Example costs: Example cost drivers: Labor wages Labor hours Supervisory salaries No. of people supervised Maintenance wages No. of mechanic hours Depreciation No. of machine hours Energy Kilowatt hours
Learning Objective 2
Show how changes in cost-driver activity levels affect variable and fixed costs.
Comparison of Variable and Fixed Costs • A variable cost 变动成本 is a cost that changes in direct proportion to changes in the cost driver • A fixed cost 固定成本 is not immediately affected by changes in the cost driver.
Costs and activities • Activities cause costs incurred. • Managers focus on their efforts on managing the activities required to make the business. • So the managers need to know how routine activities affect costs. Associating costs with activities is a key.
Fixed
Rules of Thumb
Think of fixed costs as a total. Total fixed costs remain unchanged regardless of changes in cost-driver activity.
Rules of Thumb
Think of variable costs on a per-unit basis. The per-unit variable cost remains unchanged regardless of changes in the cost-driver activity.
Y=a+b×S Unit cost = a/S + b
Learning Objective 3
Calculate break-even sales volume in total dollars and total units.
Cost –volume –profit analysis
Managers often classify costs as fixed or variable costs when making decisions that affect the volume of output
Contribution Margin Technique
Per Unit Selling price $5 Variable cost 4 Contribution margin $1
$8,000 ÷ $1 = 8,000 units
Contribution Margin Technique
Revenues = 8,000 × 5 = 40,000 Total costs = FC + VCs = 8,000 + 8,000* 4 = 40,000 Revenues = total costs, in break-even !
Relevant Range 相关范围
• This rule of thumb holds true only within reasonable limits. • The relevant range is the limit of costdriver activity within which a specific relationship between costs and the cost driver is valid.
Variable Cost Per Unit Example The cost per long distance minute talked is constant. For example, 5 cents per minute.
Per Minute Telephone Charge
Minutes Talked
Total Variable Cost Example Your total long distance telephone bill is based on how many minutes you talk.
Total Long Distance Telephone Bill
Minutes Talked
Cost Drivers
How well the accountant does at identifying the most appropriate cost drivers determines how well managers understand cost behavior and how well costs are controlled.
SP – VC = contribution margin 单位贡献毛 利
(SP – VC)/ SP = contribution margin ratio = 贡献毛利率
Break-Even Point Techniques
• There are two basic techniques for computing break-even point - Contribution margin 边际贡献 - Equation
Costs and activities
• Accountants identify the activities in their firms and determine measures of output for each activities. • Then accountants relate each output measure to the resources that are necessary to produce it.
Equation Technique
Net income equals zero at the break-even point.
Learning Objective 1
Explain how cost drivers affect cost behavior.
Costs and activities
Inputs Resources
activities
Outputs
Costs
relationship
CoSelling price (SP) $5 Percentage 100
Variable cost (VC)
$4
80
monthly fixed costs (FC)
$8,000
Break-Even Point (BE) 保本点 The break-even point is the level of sales at which revenue equals expenses and net income is zero SP × BE －(FC ＋VC × BE ) = Profit =0 BE= FC / (SP – VC)
Cost Behavior 成本习性
What is cost behavior It is how costs are related to, and affected by, the activities of an organization.
Cost Drivers 成本驱动因子
What are cost drivers Output measures of resources and activities are called cost drivers.
Relevant Range
$16,000 – Fixed Costs $12,000 – $8,000 – $4,000 Relevant Range
–
–
0
500
1,000 1,500 2,000 Volume in Units
2,500
–
Total costs
Total costs = fixed costs + variable costs = FC + VC × Drivers
Total Fixed Cost Example Your monthly basic telephone bill probably does not change when you make more local calls.
Monthly Basic Telephone Bill Number of Local Calls
Cost Classifications
Summary of Variable and Fixed Cost Behavior
Cost Variable In Total Total variable cost changes as activity level changes. Total fixed cost remains the same even when the activity level changes. Per Unit Variable cost per unit remains the same over wide ranges of activity. Fixed cost per unit goes down as activity level goes up.