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Daniel l. Rubinfeld

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5<br />

:;<br />

208 Part 2 Producers, Consumers, and Competitive Markets<br />

7 The Cost of Production 209<br />

way of fixed costs-perhaps the salaries of the top executives, some security<br />

gu~rds, and electricity. Thus, when Dell and Gateway think about ways of<br />

reducina cost the" focus laraely on oaettino a better prices for components Or<br />

b I) 0 J<br />

reducing labor requirements-both of which are ways of reducing yariable<br />

cost.<br />

What about the software programs that run on these personal com,puters<br />

Microsoft produces the Windmvs operating system as well as a \'ariety of<br />

applications such as Word, Excel, and PowerPoint. But many other finns_<br />

some large and some small-also produce software programs that run on<br />

personal computers. The costs of production for such fin~s are quite different<br />

from those facina hardware manufacturers. In sottware production<br />

o<br />

most costs are sUllk, Typically, a software firm will spend a large amount of<br />

money to develop a new application program. These expenditures cannot be<br />

recovered.<br />

Once the program is completed, the company can try to recoup its investment<br />

(and make a profit as well) by selling as many copies of the program as<br />

possible. The variable cost of producing copies of the program is very smallit<br />

is largely the cost of copying the program to Hoppy disks or CDs and then<br />

packaging and shipping the product. Like'wise, the fixed cost of production is<br />

smalL Because most costs are sunk, entering the software business can<br />

involve considerable risk. Until the development money has been spent and<br />

the product has been released for sale, an entrepreneur is unlikely to know<br />

how many copies can be sold and whether or not he ,'1'ill be able to make<br />

money.<br />

Finally, let's turn to your neighborhood pizzeria. For the pizzeria, the<br />

largest component of cost is fixed, Sunk costs are fairly low because pizza<br />

ovens, chairs, tables, and dishes can be resold if the pizzeria goes out ot business.<br />

Variable costs are also fairly low-mainly the ingredients for pizza<br />

(Hour, tomato sauce, cheese, and pepperoni for a typical large pizza might cost<br />

$1) and perhaps wages for a couple of 'workers to help produce, sen'e, and<br />

deliver the pizzas. Most of the cost is fixed-the opportunity cost of the<br />

owner's time (he might typically work a 60- or 70-hour week), rent, and utilities.<br />

Because of these high fixed costs, most pizzerias (which might charge $10<br />

for a pizza costing about $3 in variable cost to produce) don't make very<br />

7m2<br />

Cost'<br />

We begin our detailed analysis of cost with the short-run case. The distinction<br />

betvveen fixed and variable costs is important here. To decide how much to produce,<br />

managers must know how variable cost increases with the level of output.<br />

It will also be helpful to consider some other measures of cost. We will use a specific<br />

example that typifies the cost situation of many firms. After we explain eac~<br />

of the cost concepts, we will show how they relate to the analysis in Chapter 6 at<br />

the firm's production process,<br />

The data in Table 7.1 describe a firm with a fixed cost of $50. Variable cost<br />

increases 'with output, as does total cost, which is the sum of the fixed cost in colunTIl<br />

1 and the variable cost in colunu1 2. From the figures given in columns 1<br />

and 2, a number of additional cost variables can be defined.<br />

(UNITS<br />

PER YEAR)<br />

o<br />

2<br />

3<br />

4<br />

5<br />

6<br />

7<br />

8<br />

9<br />

10<br />

11<br />

FIXED<br />

COST<br />

(DOLLARS<br />

PER YEAR)<br />

(FC)<br />

(1)<br />

50<br />

50<br />

50<br />

50<br />

50<br />

50<br />

50<br />

50<br />

50<br />

50<br />

50<br />

50<br />

VARIABLE<br />

COST<br />

(DOl.LARS<br />

PER YEAR)<br />

(VC)<br />

(2)<br />

0<br />

50<br />

78<br />

98<br />

112<br />

130<br />

150<br />

175<br />

204<br />

242<br />

300<br />

385<br />

AVERAGE<br />

TOTAL MARGINAL FIXED<br />

COST COST COST<br />

(DOLLARS (DOLLARS (DOLLARS<br />

PER YEAR) PER UNIT) PER UNIT)<br />

(TC) (MC) (AFC)<br />

(3) (4) (5)<br />

50<br />

100 50 50<br />

128 28 25<br />

148 20 16}<br />

162 14 12.5<br />

180 18 10<br />

200 20 8.3<br />

225 25 7J<br />

254 29 6.3<br />

292 38 5.6<br />

350 58 5<br />

435 85 4.5<br />

Marginal cost-sometimes called illcn:lIlclltol cost-is<br />

the increase in cost that results from producing one extra unit of output. Because<br />

fixed cost does not change as the firm's le\'e! of output changes, rnarginal cost is<br />

equal to the increase in yariable cost or the increase in total cost that results from<br />

an extra unit of output. We can therefore write marginal cost as<br />

MC = ~VC/~Q = STC/~Q<br />

Marginal cost te21s us how much it will cost to expand the firm's output by<br />

one Ul11t. In Table 1.1, marginal cost is calculated from either the \'ariable cost<br />

~column 2)r the total cost (column 3). For example, the rnarginal cost of increasmg<br />

output trom 2 to 3 units is 520 because the \'ariable cost of the firm increases<br />

from S78 to 598. (The total cost of production also increases bv 520, from 5128 to<br />

51-18. Total cost differs from \'ariable cost onlv bv the fixed co~t, which bv definition<br />

does not change as output changes.) , - -<br />

. Average total cost, used interchangeably with<br />

WIth llI'cmgc ccollolllic cost, is the firm's total cost di\'ided bv its le\'e! of<br />

output, TCIQ. Thus the a\'erage total cost of producina at a rate o{ fi\'e units is<br />

536-:-that is, 5180/5. Basicall;;, ayerage total cost tells u~ the per-unit cost of produCtlOl1.<br />

ATC has two components. Average fixed cost is the fixed cost (column 1 of<br />

Table 7.1) di\'il~ed by the le\'ei of output, FCIQ.. For example, the a\'e1'­<br />

age fixed cost ot producing -1 units of output is 512.50 (550/-1). Because fixed<br />

cost is constant, a\'erage fixed cost declines as the rate of output increases.<br />

AVERAGE AVERAGE<br />

VARIABLE TOTAL<br />

COST COST<br />

(DOLLARS (DOLLARS<br />

PER UNIT) PERUNJT)<br />

(AVC) (ATC)<br />

(6) (7)<br />

50 100<br />

39 64<br />

32.7 49.3<br />

28 40.5<br />

26 36<br />

25 33.3<br />

25 32.1<br />

25.5 31.8<br />

26.9 32.4<br />

30 35<br />

35 39.5<br />

marginal cost (MC) Increase<br />

in cost resulting from the production<br />

of one extra unit of<br />

output<br />

average total cost (ATC)<br />

Firm's total cost di\'ided b\'<br />

its le\'el of output. -<br />

average fixed cost (AFC)<br />

Fixed cost di\'ided by the le\'el<br />

of output

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