2. 9-2
Economic Costs
• The payment that must be made to obtain
and retain the services of a resource
• Explicit costs
• Monetary outlay
• Implicit costs
• Opportunity cost of using self-owned
resources
• Value of next-best use
• Includes a normal profit
LO1
5. 9-5
Economics Profit Example
• Michael can mow the lawn for $40 per hour.
He spends $5 on gasoline and uses $10 worth
of equipment (depreciation).
• Michael’s accounting profit
= $40 - $15 = $25
• Instead, Michael can work at Home Depot as
sales clerk and earn $10 per hour.
• Michael’s economic profit
= $40 - $15 - $10 = $15
6. 9-6
Economic Profit Example
• If Michael can earn only $25 per hour to mow
the lawn, which job should he choose?
• If Michael can earn only $20 per hour to mow
the lawn, which job should he choose?
7. 9-7
Short Run and Long Run
• Short run
• Some variable inputs
• Fixed plant
• Long run
• All inputs are variable
• Firms can adjust plant size as well as enter
and exit industry
LO2
8. 9-8
Short Run Production
Relationships
• Total product (TP): Total quantity of output
for given inputs
• Marginal product (MP)
• Average product (AP)
LO2
Marginal product change in total product
change in labor input
=
Average product total product
units of labor
=
9. 9-9
Marginal Return
• Increasing marginal returns occur when the
marginal product of an additional variable
input exceeds the marginal product of the
previous input.
• Decreasing marginal returns occur when the
marginal product of an additional variable
input is less than the marginal product of the
previous input.
10. 9-10
Total, Marginal, and Average Product: The Law of Diminishing Returns
(1)
Units of the Variable
Resource (Labor)
(2)
Total Product (TP)
(3)
Marginal Product
(MP)
Change in (2)/
Change in (1)
(4)
Average Product
(AP),
(2)/(1)
0 0 -
1 10 10 Increasing
marginal
returns
10.00
2 25 15 12.50
3 45 20 15.00
4 60 15
Diminishing
marginal
returns
15.00
5 70 10 14.00
6 75 5 12.50
7 75 0 10.71
8 70 -5 Negative
marginal
returns
8.75
7-10
The Law of Diminishing Returns
12. 9-12
Law of Diminishing Returns
• Law of diminishing returns
• Resources are of equal quality
• Technology is fixed
• Variable resources are added to fixed
resources
• At some point, marginal product will fall
LO2
13. 9-13
Short Run Production Costs
• Fixed costs (TFC)
• Costs that do not vary with output
• Costs associated with variable input
• Variable costs (TVC)
• Costs that do vary with output
• Costs associated with fixed input
• Total cost (TC)
• Sum of TFC and TVC: TC = TFC + TVC
LO3
14. 9-14
Short-Run Production Costs
LO3
Total, Average, and Marginal Cost Schedules for an Individual Firm in the Short Run
Total Cost Data Average Cost Data Marginal Cost
(1)
Total Product
(Q)
(2)
Total Fixed Cost
(TFC)
(3)
Total Variable
Cost
(TVC)
(4)
Total Cost (TC)
TC=TFC+TVC
(5)
Average Fixed
Cost
(AFC)
AFC = TFC/Q
(6)
Average
Variable
Cost
(AVC)
AVC=TVC/Q
(7)
Average Total
Cost
(ATC)
ATC = TC/Q
(8)
Marginal Cost
(MC)
MC =ΔTC/ΔQ
0 $100 $0 $100
1
100
90 190 $100.00 $90.00 $190.00 $90
2 100 170 270 50.00 85.00 135.00 80
3 100 240 340 33.33 80.00 113.33 70
4 100 300 400 25.00 75.00 100.00 60
5 100 370 470 20.00 74.00 94.00 70
6 100 450 550 16.67 75.00 91.67 80
7 100 540 640 14.29 77.14 91.43 90
8 100 650 750 12.50 81.25 93.75 110
9 100 780 880 11.11 86.67 97.78 130
10 100 930 1030 10.00 93.00 103.00 150
7-14
16. 9-16
Per-Unit, or Average, Costs
• Average fixed cost AFC = TFC/Q
• Average variable cost AVC = TVC/Q
• Average total cost ATC = TC/Q
• Marginal cost MC = ΔTC/ΔQ
LO3
19. 9-19
Marginal Cost and Marginal Product
• Figure illustrates the relationship
between the product curves and
cost curves.
• A firm’s marginal cost curve is
linked to its marginal product
curve.
• If marginal product rises, marginal
cost falls.
• If marginal product is a maximum,
marginal cost is a minimum.
20. 9-20
Marginal Cost and Marginal Product
• A firm’s average variable cost
curve is linked to its average
product curve.
• If average product rises, average
variable cost falls.
• If average product is a maximum,
average variable cost is a
minimum.
21. 9-21
Marginal Cost and Marginal Product
• At small outputs,
• MP and AP rise and
• MC and AVC fall.
• At intermediate outputs,
• MP falls and MC rises and
• AP rises and AVC falls.
• At large outputs,
• MP and AP fall and
• MC and AVC rise.
22. 9-22
Technology Change
• A technological change that increases
productivity shifts the TP curve upward. It also
shifts the MP curve and the AP curve upward.
• With a better technology, the same inputs can
produce more output, so an advance in
technology lowers the average and marginal
costs and shifts the short-run cost curves
downward.
23. 9-23
Change in Prices of Factors of
Production
• An increase in the price of a factor of
production increases costs and shifts the cost
curves.
• But how the curves shift depends on which
resource price changes.
24. 9-24
Long Run Production Costs
• The firm can change all input amounts,
including plant size
• All costs are variable in the long run
• Long run ATC: the lowest average cost at
which it is possible to produce each output
when the firm has had sufficient time to
change both its plant size and labor employed.
• Different short run ATCs
LO4
27. 9-27
Economies of Scale
• Economies of scale (Increasing return to
scale): when a firm increases its plant size and
labor employed by the same percentage, its
output increases by a larger percentage and
average total cost decreases.
• Labor specialization
• Managerial specialization
• Efficient capital
• Other factors
LO4
28. 9-28
Constant Return to Scale
• Constant returns to scale: if when a firm
increases its plant size and labor employed by
the same percentage, its output increases by
the same percentage and average total cost
remains constant.
• a firm is able to replicate its existing
production facility including its
management system.
29. 9-29
Diseconomies of Scale
• Diseconomies of scale (Decreasing return to
scale): when a firm increases its plant size and
labor employed by the same percentage, its
output increases by a smaller percentage and
average total cost increases.
• Control and coordination problems
• Communication problems
• Worker alienation
• Shirking
LO4
30. 9-30
MES and Industry Structure
• Minimum efficient scale (MES)
• Lowest level of output at which long run
average costs are minimized
• Can determine the structure of the industry
• Natural monopoly
• Long run costs are minimized when one
firm produces the product
LO4
31. 9-31
MES and Industry Structure
Output
Averagetotalcosts
Long-run
ATC
Economies
of scale
Constant returns
to scale
Diseconomies
of scale
q1 q2
LO5
32. 9-32
MES and Industry Structure
Output
Averagetotalcosts
Economies
of scale
Diseconomies
of scale
Long-run
ATC
LO5
Notes de l'éditeur
This chapter develops a number of crucial cost concepts that will be employed in the succeeding three chapters to analyze the four basic market models. A firm’s implicit and explicit costs are explained for both short and long run periods. The explanation of short run costs includes arithmetic and graphic analyses of both the total, average, and marginal-cost concepts. These concepts prepare students for both the total-revenue minus total-cost and marginal-revenue = marginal-cost approaches to profit maximization, which are presented in the next few chapters.
The law of diminishing returns is explained as an essential concept for understanding average and marginal cost curves. The general shape of each cost curve and the relationship they bear to one another are analyzed with special care.
The final part of the chapter develops the long run average cost curve and analyzes the characteristics and factors involved in economies and diseconomies of scale. In the Last Word, there is a discussion about 3-D printers, a new technology that may revolutionize manufacturing.
Economic costs are the payments a firm must make, or incomes it must provide, to resource suppliers to attract those resources away from their best alternative production opportunities. Payments may be explicit or implicit. (Recall the opportunity-cost concept)
Explicit costs are payments to non-owners for resources they supply. In the textbook’s T-shirt example, this would include the cost of the T-shirts, clerk’s salary, and utilities, for a total of $63,000.
Implicit costs are the money payments the self‑employed resources could have earned in their best alternative employment. In the textbook’s T-shirt example, this would include forgone interest, forgone rent, forgone wages, and forgone entrepreneurial income, for a total of $33,000.
Economic or pure profits are total revenue less all costs (explicit and implicit including a normal profit). Economic profit will always be smaller than an accounting profit, which excludes implicit costs. The normal profit is the return to the entrepreneur and is the amount of money required by the entrepreneur to stay in that market.
Economic profit versus accounting profit. Economic profit is equal to total revenue less economic costs. Economic costs are the sum of explicit and implicit costs and includes a normal profit to the entrepreneur. Accounting profit is equal to total revenue less accounting (explicit) costs.
The short run is a period of time that is too brief for a firm to alter its plant capacity, but can change output somewhat by increasing or decreasing its variable inputs. The long run is a period of time that is long enough for the firm to adjust the plant size as well as enter or leave the industry. All inputs are variable in the long run. One of the primary characteristics of the long run is that it is enough time for firms to enter and exit the industry. Notice that the actual time associated with the short and long run will differ among industries. Light industry and retailing (small t-shirt manufacturer) can adjust quickly compared to heavy industry (an oil company) which may take years to change capacity.
The production relationships reflect how labor and output are related in the short run. The total product is the total quantity that is produced. Marginal product (MP) is the amount that total product changes when labor changes by one unit. It reflects the change in output when one more unit of labor is hired. Average product is the output that is produced per unit of labor.
You can see that at first TP is rising at an increasing rate. So MP is positive and getting larger. This is called increasing marginal returns. Then TP continues to increase, but by smaller and smaller amounts. This is called diminishing marginal returns. TP is still positive and rising but it is now rising at a slower rate. MP measures the rate of change of TP. So, when the firm has hired so many workers that it is overcrowded and impedes the workers’ abilities to produce, the TP starts to fall and MP becomes negative. AP starts out increasing due to increasing marginal returns. Then, at some point, AP will begin to fall as a result of the effects of diminishing marginal returns. It takes AP longer to reflect the diminishing marginal returns.
The law of diminishing returns states as a variable resource (labor) is added to fixed amounts of other resources (land or capital). The total product that results will eventually increase by diminishing amounts, reach a maximum, and then decline.
Marginal product is the change in total product associated with each new unit of labor. Average product is simply output per labor unit. Note that marginal product intersects average product at the maximum average product.
As successive increments of a variable resource are added to a fixed resource, the marginal product of the variable resource will decrease. Essentially the fixed plant gets overcrowded with variable resources. If we focus on labor being the variable resource, when there isn’t any labor, then the plant is underused because none of the machinery is being used, etc. When hiring one unit of labor, the machinery is still underused – there is machinery that is often idle as that one unit of labor has to perform all of the tasks. As the firm continues to hire more and more labor, the TP is rising by increasing amounts because the machinery is being used more and more to its capacity. However, at some point there will be so much labor that the fixed resources are overutilized and the individuals will have to wait to use the necessary equipment. This is where we might see diminishing marginal returns – where the TP is still increasing when hiring one more unit of labor, but it doesn’t increase as much as it did with the previous unit of labor.
The table on the next slide presents a numerical example of the law of diminishing returns.
Fixed, variable and total costs are the short‑run classifications of costs. In the short run, costs can be variable or fixed. Fixed cost examples: rental payments, insurance premiums, interest payments. Variable cost examples: payments for materials, fuel, power, transportation services, labor. Total cost is the sum of total fixed and total variable costs at each level of output.
This table shows total costs on the left half and per unit costs on the right half for an individual firm in the short run. We know this is the short run because there are fixed costs.
Total fixed cost (TFC) is independent of the level of output. Total cost is the sum of fixed cost and variable cost. Total variable cost (TVC) changes with output.
Since the only thing that differentiates the TC and TVC is the constant fixed costs, the TC and TVC look very similar and are parallel to each other. The total cost (TC) at any output is the vertical sum of the fixed cost and variable cost at that output.
These per-unit costs are useful in making comparisons to price. Average fixed costs reflect the fixed costs per unit produced whereas the average variable costs reflect the variable costs per unit produced. The average total costs can also be found by adding the AFC and AVC. Marginal costs play an extremely important role in the firm’s decision-making about how much they will produce. Marginal costs reflect the additional cost associated with producing one more unit of output. MC tells a firm how much it will cost to increase output by 1 more unit. Marginal cost essentially measures the rate of the change of the total costs.
AFC falls as a given amount of fixed costs is apportioned over a larger and larger output. AVC initially falls because of increasing marginal returns but then rises because of diminishing marginal returns. Average total cost (ATC) is the vertical sum of average variable cost (AVC) and average fixed cost (AFC). The only difference between the ATC and AVC is the AFC (remember ATC= AFC+AVC or AFC = ATC-AVC), so the vertical distance between the ATC and AVC is the AFC. You want to get used to measuring AFC in this way because at some point, the AFC will no longer be included in the graphs.
Shifts in the curves will occur if either resource prices or technology change. For example, if fixed costs increase, both AFC and ATC shift up. If labor costs (or some other variable input costs) rise, then the AVC, ATC, and MC would shift up.
Figure 9.5 This graph shows the relationship of the marginal-cost curve to the average-total-cost and average-variable-cost curves. The marginal-cost (MC) curve cuts through the average-total-cost (ATC) curve and the average-variable-cost (AVC) curve at their minimum points. When MC is below average total cost, ATC falls; when MC is above average total cost, ATC rises. Similarly, when MC is below average variable cost, AVC falls; when MC is above average variable cost, AVC rises. Marginal decisions are very important in determining profit levels. In order to make marginal decisions, marginal revenue and marginal cost are compared. Marginal cost is a reflection of marginal product and diminishing returns. When diminishing returns begin, the marginal cost will begin its rise.
The marginal-cost (MC) curve and the average-variable-cost (AVC) curve are mirror images of the marginal-product (MP) and average-product (AP) curves. Assuming that labor is the only variable input and that its price (the wage rate) is constant, then when MP is rising, MC is falling, and when MP is falling, MC is rising. Under the same assumptions, when AP is rising, AVC is falling, and when AP is falling, AVC is rising.
An industry and the individual firms that are in it can make all desired resource adjustments in the long run. All resources are variable, therefore all costs are variable in this time period.
Any number of short-run optimum size cost curves can be constructed. The long-run average-total-cost curve is made up of segments of the short-run cost curves (ATC-1, ATC-2, etc.) of the various-size plants from which the firm might choose. The long run cost curve is also called the planning curve. Each point on the bumpy planning curve shows the lowest unit cost attainable for any output when the firm has had time to make all desired changes in its plant size.
The long-run ATC curve just “envelopes” the short run ATCs. If the number of possible plant sizes is very large, the long-run average-total-cost curve approximates a smooth curve. Economies of scale, followed by diseconomies of scale, causes the curve to be U-shaped.
Economies of scale refers to the idea that, for a time, larger plant sizes will lead to lower unit costs. An increase in inputs where there are economies of scale will lead to a more than proportionate increase in output. Labor specialization leads to economies of scale because it makes use of special skills; proficiency is gained as the worker concentrates on one task and time is saved. Managerial Specialization leads to economies of scale because managers can manage more workers with no increased cost, and managers can specialize in their respective area of expertise. Efficient Capital leads to economies of scale because high volume production warrants the expensive large scale equipment. Other factors lead to economies of scale because costs such as design, development, and advertising are spread out over larger quantities.
Constant returns to scale will occur when ATC is constant over a variety of plant sizes. When there are constant returns to scale, an increase in inputs will result in a proportionate increase in output.
Diseconomies of scale may occur if a firm becomes too large, as illustrated by the rising part of the long run ATC curve. As the firm expands over time, the expansion may lead to higher average total costs. With diseconomies of scale, an increase in inputs will cause a less than proportionate increase in output.
Reasons that diseconomies of scale may occur: 1) difficulty in controlling and coordinating large scale operations, 2) a large bureaucracy leads to communication problems, 3) workers may feel alienated and therefore may not work efficiently and 4) shirking, or work avoidance, may be easier in a larger firm.
Where MES occurs on an industry’s long-run ATC determines if there will be many or few producers and whether they will be large, small, or different sizes. A natural monopoly is a rare situation where economies of scale extend beyond the market size. Therefore, one large firm can provide the product more cheaply than a multi-firm market.
This is a long-run ATC curve showing industries with an extended range of constant returns to scale. These industries will be populated by firms of many different sizes. Small and large scale producers will coexist and be equally successful. MES occurs at an output of q1.
Industries with economies of scale over a wide range of outputs will lead to a few large scale firms. The long-run ATC curve is lowest only when there is a large output.