14 Theory of Cost-II

Dr. Savita

  1. Introduction

 

In the context of production theory, long-run is defined as a period in which all the inputs become variable. The variability of inputs is based on the assumption that in the long run, supply of all the inputs, including capital equipment and factory building, becomes elastic. So the long run is a period in which there is sufficient time to alter the scale of production or equipment or the organization with a view to produce different quantities of output. The firms are therefore in a position to expand the scale of their production by hiring a more quantity of all the inputs. In the long period all factors of production are variable and there is no distinction between fixed and variable costs. All the costs are variable costs. All the factors, building, machines and even employees and organization are changeable. In the long run, the firm has enough time to bring about change in fixed factor of production. So in the long run we have three types of costs:

  • Long run Total cost
  • Long run Average cost
  • Long run Marginal cost
  1. Long run Total cost: Long run total cost is always equal or less than the short run total cost, but it is not more than the short run total cost. Long run total cost curve represents the least cost of different quantities of output.

The shape of the long-run total cost curve is S-shaped, which is very similar to a short-run total cost curve. When there is small scale of output, the slope begins to flatten. Then for large scale the slope makes a turn-around and becomes steeper. The flattening portion of this long-run total cost curve is due to economies of scale or increasing returns to scale. The steepening portion is then due to diseconomies of scale or decreasing returns to scale.

  1. Long run Average cost: Long run Average cost is the long run total cost divided by the level of output. Long run average cost curve shows the least possible average cost for producing different levels of output. So Average cost is the minimum cost which a producer faces by producing different quantities of output in a long run. In order to understand, consider the three short term Average cost curves. These short run Average cost curves are also called Plant curves. Suppose a firm has three plants with different sizes, plant one with small,plant two with minimum and plant third with large size. The cost curve of small plant is presented by SAC1 and medium size by SAC2 and large size with SAC3. This is shown in the following figure.

So in the short run average cost curve the firm will increase or decrease its output by varying the amount of the variable outputs. But, in the long run, the firm can choose among the three possible sizes of plant as depicted by short run average cost curves SAC1, SAC2 and SAC3. In the long run the firm will examine with which size of plant or on which short run SAC2 curve it should operate to produce a given level of output at the minimum possible cost.

 

Let us take another assumption now, there are large number of plants, with different sizes, then the curve which will reflect the minimum cost of production of each plant will be the long run average cost curve of the firm. Each point lying on this curve shows the least cost for producing the corresponding level of output. The long run average cost is the locus of point denoting the least cost or minimum cost of producing the corresponding output. This LAC helps a producer to decide what plant to set up in order to produce at a minimum cost at the expected level of output of a commodity.

 

This is also known as Planning curve as it serves as a guide to the producer in his plan to expand production, with its help, a firm can plan as to which plant, it should use to produce different quantities of output so that production is obtained at minimum cost. So the long run average cost curve reveals to the firm that how large should be the plant for producing a certain output at the least possible cost.

 

It is also known as Envelope curve, because it is the sum of all short run average cost curve in it or it envelopes the short run average cost curves. It shows that average cost in the long run cannot exceed the short run average cost. This is shown in following figure:

 

Relationship between LAC and SAC

 

LAC and SAC both are cost curves. LAC represents the cost of different plants whereas SAC represents the cost of single plant. The relationship between LAC and SAC can be explained with the help of following figure:

 

 

By considering this figure, we can draw a following relationship between LAC and SAC.

  • Like SAC, LAC is also U-shaped but it is relatively flatter. It shows that, in the long run, increase or decrease in costs relatively less.
  • LAC cannot be more than SAC because, LAC is tangent to SAC.
  • SAC represents the cost of single plant whereas LAC represents the costs of different plants.
  1. Long run Marginal Cost: Change in total cost due to change in output by producing one more unit is marginal cost. The marginal cost is the addition made to total cost by producing one more unit of output. In other words, marginal cost may be defined as the change in total cost associated with a one unit change in output. It is also termed as ‘Cost of extra unit’ or incremental cost, as it measures the amount by which total cost increases when output is expended by one unit. The relation of LMC with LAC will be the same as the relation of SMC with SAC. LMC curve also cut LAC curve at its lowest point. LMC curve is flatter than SMC curve. It can be shown with the help of following figure.

It is clear from this figure that the long run marginal cost curve LMC, like the long run average cost curve LAC, is U- shaped. But the long run LMC is flatter than the short run marginal cost curves.

 

Relationship between LMC and LAC

 

Basically, the relation between the long run marginal cost and the short run average cost is almost the same but the only difference in LAC and LMC is that long run marginal and average costs are more flatter than SAC and SAC and SMC. The reason behind is the variability of all factors of production. It should be remembered that the relationship between the long run marginal cost curve LMC and the long run average cost curve LAC is the same as that between the short run marginal cost curve and the short run average cost. It can be shown with help of following figure.

 

 

The Modern Theory of Cost Curves

 

Earlier it was believed that both the short run and the long run cost curves have a U shape. But in recent years, has been observed that in real life, the cost curves are Saucer- shaped or L- shaped. The theory which explains its new shape is called the modern theory of cost curves. The Modern theory of cost curves has been propounded by economists like Andrew, Stigler, Sergeant Florence and Friedman. Modern theory is based on empirical evidences, the short run SAVC and SMC coincide with each other and a horizontal straight line over a wide range over output. So the nature of short run and the long run cost curves under modern theory are given below:

 

Short run cost curves under modern theory of cost: The short run cost curves are derived from the total cost which is the sum total of fixed cost and variable cost. So like traditional theory, modern theory of cost curve also have the short run cost curves such as AFC, SAVC, SAC and SMC.

AFC: Average fixed cost is the cost of indirect factors of the firm. In simple words we can say that, the cost of physical and personal organization of the firm. Costs such as the salaries of the staff involved directly in production but paid on a fixed term basis, depreciation of machinery, and maintenance expenses of factory building etc.

 

SAVC: The average variable cost includes wages of labour employed, cost of raw materials, and day today expenses of machinery. The SAVC curve in modern theory of cost is Saucer-shaped. That is broadly U shaped. It has a flat stretch over a range of output. This flat stretch represents the built in reserve capacity of plant. The falling portion of SAVC shows reduction in cost due to better utilization of fixed factors, improvement in the skill and efficiency of labour and less wastage of raw material. On the other hand, rising portion of the SAVC curve shows the inefficiency of labour, frequent break down of machinery and the wastage of raw material.

 

SAC: According to the modern theory of cost SAC is continuously falling up to a given level of output. This given level of output represents the reserved capacity of output.

 

SMC: In initial stags SMC in modern theory of cost, falls and then becomes horizontal. The main difference is about the shapes of the curves. In simple words we can say that in modern theory these short run costs curves have a saucer shape or bowl shape instead of U shaped. In modern theory, short run cost curves  have  been investigated  by economists on the  basis of  empirical  studies  behaviour  pattern. According to this theory, the firm chooses only that plant which can be run with the available variable direct factors and the one which has a great flexibility with some reserve capacity. The basic objective of installation such type of plant is to produce maximum output in order to meet any increase in demand for its product. The SAVC and SMC curves are shown below in the figure. It shows falling of both the curves up to point A and SMC curve lies below the SAVC curve. Falling SAVC shows the optimum utilization of fixed factors and increase of productivity of the variable factor that causes the reduction in cost.

Plants can attain that level with better utilization of available resources, better skills and less wastage in raw material. The Saucer- shaped SAVC curve has a flat stretch over Q1 –Q2 as far as output concerned, it shows application of constant returns to scale. Divisibility of fixed factors is the main reason behind the saucer shape of SAVC curve. After reaching to the point B, both curves have started rising, which shows increase in costs. This increased cost may be due to increase in wastage of raw material, frequent breakdowns, lack in labour productivity and overtime payment to labour . When SAVC is rises after the full utilization of the reserve capacity of the plant, SMC curve lies above it.

 

SAC is obtained by adding the average fixed cost to the average variable cost. As shown in the following figure AFC falls as the output is extended. The SAC falls up to the level of output at which the reserve capacity is fully exhausted i.e. up to the OQ level. Afterward SAC rises with the increase in output. At point M, SAC intersect SMC, this is because of steeply rising SAVC from point E and on the other side AFC is falling at low rate.

 

 

Long-run cost curves under Modern theory of cost: As the output increases, the firm’s average cost of producing that output is likely to decline, at least to a point. This can happen for the following reasons:

 

Modern theory of cost explains that long term cost curves have an L shape instead of U shape. First the LAC curve falls, then remains flat or may slope downward to its right hand side. Some economists have given the following reasons for the L-shape of the LAC.

 

1.Production or technical economies: As we know, in the long period all the costs are variable costs. Whenever the firm thinks about the effect of expansion of output on the average cost, the production and the managerial costs are taken in to consideration. With increase in the scale of production, its production cost falls in the beginning and then gradually keeps on falling. That happens because of technical economies of large scale. Therefore, a firm producing on large scale can enjoy the economies by the use of superior techniques. Modern technology is highly specialized. The advanced technology makes it possible to conceive the whole process of production of a commodity in one composite unit of production. For example, the production of cloth in a textile mill may comprise of such plants as Spinning, Weaving, Printing, Packing etc. The Technical economies are of three types:

 

Economies of dimension: When a firm increases its scale of production, the average cost of production falls but its average return will be more.

 

Economies of by-product: When a firm increases its scale then it is in a position    to use its by-products and waste material to produce another material.

 

Economies of linked process: As the scale of production increases, firm carries all productive activities. These activities get economies. These linked activities save time and transport cost of the firm.

 

Labour Economies: When a firm’s scale of production expands, more and more workers of varying skill and qualification are employed. With the employment of large number of workers, it becomes increasingly possible to divide the labour according to their qualifications and skills and assign them the function to which they are best suited. The workers are skilled in their operation which reduces cost, increases the productivity and saves the time. But after achieving all the economies, the firm reaches at MES that is to the minimum optimal scale.

  1. Managerial cost: The Managerial Economies arise from specialization in managerial activities and mechanization of managerial functions. For a large firm, it becomes possible to divide its management into specialized departments under specialized personnel, such as the production manager, the sales manager, the personnel manager, etc. This increases the efficiency of management at all levels of management because of decentralization of decision making. It increases production, given the cost, large scale firms have the opportunity to use advanced techniques of communication, telephones and telex machines, computers, and their own means of transport. All these lead to quick decision making, which thereby helps in saving the valuable time of the management and hence improves the managerial efficiency.

 

Marketing Economies: In the marketing economies, we include the advertisement economies, the opening up of showrooms, the appointment of sole distributors etc. Moreover, a large firm can conduct its own research to affect improvement in the quality of product and to reduce the cost of production. With the expansion of the firm, the total production increases. But the expenditure on advertising the product does not increase proportionately. Similarly, selling through the wholesale dealers reduces the cost of distribution of the firm’s production.

 

Technical progress: Another major reason for L-shaped cost curve is the technical progress. As a result of technological progress in the real world, the long run average cost curve will shift downward over the period. It is assumed in the traditional theory that there is no technical progress, but empirical result confirms the existence of technological progress in firms. It is shown with the help of following diagram. In this figure, it is shown that when technological progress takes place the long run average cost curve shows a falling trend.

It is shown in the diagram that if firm introduces new technology then its cost will be lower.

  1. Learning process: The learning process also contributes a lot in L- shaped cost curves. People always learn while doing something. The greater the amount of work done, the lower will be its cost. It is well known fact that the experienced people will do the work in better way and thus it reduces the cost of production and increases the productivity. A firm learns to produce a commodity more efficiently as the aggregate amount of output produced by it increases over time. The best example of learning by doing is a new firm which produces their product for the first time. After producing the first unit, they may be able to reduce the time required for second unit. And if they are able to do so it will reduce their cost of production.So along with the technological progress, learning process also provides us with the reason that why long run average cost curve is L shaped rather than U shaped. To quote stonier and Hague, “ Even with a given technology, a firm can learn to produce at a lower unit cost the longer the period of time that has elapsed since a previous observation and the greater the aggregate amount of that product that has consequently been made. It may be therefore concluded that technological change is not the only reason why long- run average cost curves are L- shaped rather than having U- shape”.

 

Summary

 

Long-run is defined as a period in which all the inputs become variable. The variability of inputs is based on the assumption that in long run, supply of all the inputs, including the capital equipment and the factory building, becomes elastic. So the long run is a period in which there is sufficient time to alter the scale of production or equipment or the organization with a view to produce different quantities of output. The firms are therefore in a position to expand the scale of their production by hiring a more quantity of all the inputs. In long period all factors of production are variable and there is no distinction between the fixed and the variable costs. All the costs are variable costs. In recent years, it is observed that in the real life, the cost curves are Saucer- shaped or L- shaped. The theory which explains its new shape is called the modern theory of cost curves. The Modern theory of cost curves has been propounded by economists like Andrew, Stigler, Sergeant Florence and Friedman. The Modern theory is based on the empirical evidences, the short run SAVC and the SMC coincide with each other and a horizontal straight line over a wide range of output

 

Few important sources to learn more about Managerial Economics:

1. Peterson, Lewis, Managerial Economics, Prentice Hall of India, N. Delhi.

2.  Salvatore, Managerial Economics in Global Economy; Thomson learning; Bombay.

3.  EF. Brigham And J,L. Pappas, Managerial Economics, Dryden Press, illinois.

4. Dwivedi, D.N. Managerial Economics, Vikas Publishing House, New Delhi.

5. Mehta, P.L. Managerial Economics, Sultan Chand, New Delhi.

6. http://mms-notes.blogspot.com/2013/07/managerial-economics.html

7. https://www.quora.com/What-are-the-roles-managerial-economics-for-a-manager

8. http://www.slideshare.net/rathourvikash/intro-to-business-economics

9. http://www.freewebs.com/vssriram/SCDL/Managerial%20Economics%20Consolidated.xls