Chapter SevenCopyright 2009 Pearson Education, Inc. Publishing as Prentice Hall. 1 Chapter 7 The Theory and Estimation of Cost.

Chapter Seven Copyright 2009 Pearson Education, Inc. Publishing as Prentice Hall.

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Chapter 7

The Theory and Estimation of Cost


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Overview

Definition and use of costRelating production and costShort run and long run costEconomies of scope and scaleSupply chain managementWays companies have cut costs to remain competitive


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Learning objectives

define the cost function

distinguish between economic cost and accounting cost

explain how the concept of relevant cost is used


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Learning objectives

understand total, variable, average and fixed cost

distinguish between short-run and long-run cost

provide reasons for the existence of economies of scale


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Importance of costin managerial decisions Ways to contain or cut costs popular

during the past decade

most common: reduce number of people on the payroll

outsourcing components of the business

merge, consolidate, then reduce headcount


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Definition and use of cost in economic analysis Relevant cost: a cost that is affected by a

management decision Historical cost: cost incurred at the time of

procurement Opportunity cost: amount or subjective

value that is forgone in choosing one activity over the next best alternative

Incremental cost: varies with the range of options available in the decision

Sunk cost: does not vary in accordance with decision alternatives


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Relationship between production and cost

Cost function is simply the production function expressed in monetary rather than physical units

We assume the firm is a ‘price taker’ in the input market


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Relationship between production and cost Total variable cost (TVC) = the cost

associated with the variable input, found by multiplying the number of units by the unit price

Marginal cost (MC) = the rate of change in total variable cost

The law of diminishing returns (Chapter 6) implies that MC will eventually increase

MP

W

Q

TVCMC


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Relationship between production and cost

Plotting TP and TVC illustrates that they are mirror images of each other

When TP increases at an increasing rate, TVC increases at a decreasing rate


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Short-run cost function For simplicity use the following assumptions:

the firm employs two inputs, labor and capital the firm operates in a short-run production

period where labor is variable, capital is fixed the firm produces a single product the firm employs a fixed level of technology the firm operates at every level of output in the

most efficient way the firm operates in perfectly competitive input

markets and must pay for its inputs at a given market rate (it is a ‘price taker’)

the short-run production function is affected by the law of diminishing returns


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Short-run cost function Standard variables in the short-run cost

function:

Quantity (Q) is the amount of output that a firm can produce in the short run

Total fixed cost (TFC) is the total cost of using the fixed input, capital (K)


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function:

Total variable cost (TVC) is the total cost of using the variable input, labor (L)

Total cost (TC) is the total cost of using all the firm’s inputs,

TC = TFC + TVC


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function:

Average fixed cost (AFC) is the average per-unit cost of using the fixed input K AFC = TFC/Q

Average variable cost (AVC) is the average per-unit cost of using the variable input L AVC = TVC/Q


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function:

Average total cost (AC) is the average per-unit cost of all the firm’s inputs AC = AFC + AVC = TC/Q

Marginal cost (MC) is the change in a firm’s total cost (or total variable cost) resulting from a unit change in output MC = TC/Q = TVC/Q


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Short-run cost function Graphical example of the cost variables


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Short-run cost function Important observations

AFC declines steadily when MC = AVC, AVC is at a minimum when MC < AVC, AVC is falling when MC > AVC, AVC is rising

The same three rules apply for average cost (AC) as for AVC


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Short-run cost function A reduction in the firm’s fixed cost would

cause the average cost line to shift downward

A reduction in the firm’s variable cost would cause all three cost lines (AC, AVC, MC) to shift


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Short-run cost function Alternative specifications of the Total Cost

function (relating total cost and output)

cubic relationshipas output increases, total cost first

increases at a decreasing rate, then increases at an increasing rate


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Short-run cost function Alternative specifications of the Total Cost

function (relating total cost and output)

quadratic relationshipas output increases, total cost

increases at an increasing rate

linear relationshipas output increases, total cost

increases at a constant rate


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Long-run cost function In the long run, all inputs to a firm’s

production function may be changed

because there are no fixed inputs, there are no fixed costs

the firm’s long run marginal cost pertains to returns to scale

at first increasing returns to scale, then as firms mature they achieve constant returns, then ultimately decreasing returns to scale


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Long-run cost function When a firm experiences increasing

returns to scale:

a proportional increase in all inputs increases output by a greater proportion

as output increases by some percentage, total cost of production increases by some lesser percentage


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Long-run cost function Economies of scale: situation where a

firm’s long-run average cost (LRAC) declines as output increases

Diseconomies of scale: situation where a firm’s LRAC increases as output increases

In general, the LRAC curve is u-shaped.


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Long-run cost function Reasons for long-run economies

specialization of labor and capital prices of inputs may fall with volume

discounts in firm’s purchasing use of capital equipment with better

price-performance ratios larger firms may be able to raise funds

in capital markets at a lower cost larger firms may be able to spread out

promotional costs


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Long-run cost function Reasons for diseconomies of scale

scale of production becomes so large that it affects the total market demand for inputs, so input prices rise

transportation costs tend to rise as production grows, due to handling expenses, insurance, security, and inventory costs


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Long-run cost function In long run, the firm can

choose any level of capacity

Once it commits to a level of capacity, at least one of the inputs must be fixed. This then becomes a short-run problem

The LRAC curve is an envelope of SRAC curves, and outlines the lowest per-unit costs the firm will incur over a range of output


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Learning curve Learning curve: line showing the

relationship between labor cost and additional units of output

• downward slope indicates additional cost per unit declines as the level of output increases because workers improve with practice


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Learning curve Learning curve:• measured in terms of percentage decrease

in additional labor cost as output doubles Yx = Kxn

Yx = units of factor or cost to produce the xth unit K = factor units or cost to produce the Kth (usually first) unit x = product unit (the xth unit) n = log S/log 2 S = slope parameter


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Economies of scope Economies of scope: reduction of a

firm’s unit cost by producing two or more goods or services jointly rather than separately

Closely related to economies of scale


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Supply chain management Supply chain management (SCM):

efforts by a firm to improve efficiencies through each link of a firm’s supply chain from supplier to customer

• transaction costs are incurred by using resources outside the firm

• coordination costs arise because of uncertainty and complexity of tasks

• information costs arise to properly coordinate activities between the firm and its suppliers


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Supply chain management Ways to develop better supplier

relationships

strategic alliance: firm and outside supplier join together in some sharing of resources

competitive tension: firm uses two or more suppliers, thereby helping the firm keep its purchase prices under control


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Ways companies cut costs to remain competitive the strategic use of cost reduction in cost of materials using information technology to reduce

costs reduction of process costs relocation to lower-wage countries or

regions mergers, consolidation, and subsequent

downsizing layoffs and plant closings


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Global application Example: manufacturing chemicals in

China

labor content relatively low high use of equipment and raw

materials noncost reasons for outsourcing

Chapter SevenCopyright 2009 Pearson Education, Inc. Publishing as Prentice Hall. 1 Chapter 7 The Theory and Estimation of Cost.

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