An Introduction to Economies & Diseconomies of Scale
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As a firm grows, it is able to increase its scale of output, generating efficiencies that lower its average costs (AC) of production
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These efficiencies are called economies of scale
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Economies of scale help large firms lower their costs of production beyond what small firms are able to achieve
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As a firm continues to increase its scale of output, it will reach a point where its average costs (AC) will start to increase
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The reasons for the increase in average costs are called diseconomies of scale
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Economies of scale are the reason that firms generate increasing returns to scale in the long run
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Diseconomies of scale are the reason that firms experience decreasing returns to scale in the long run
Diagram: Long-run Average Cost Curve

Diagram analysis
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With relatively low levels of output, the firms average costs are high
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As the firm increases its output, it begins to benefit from economies of scale, which lower the average cost per unit
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At some level of output, a firm will not be able to reduce costs any further; this point is called productive efficiency
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Beyond this level of output, the average cost will begin to rise as a result of diseconomies of scale
Types of Internal Economies of Scale
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Internal economies of scale occur as a result of the growth in the scale of production within the firm
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There are several factors that can generate internal economies of scale
Types of Internal Economies of Scale
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Internal Economy of Scale |
Explanation |
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Types of External Economies of Scale
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External economies of scale occur when there is an increase in the size of the industry in which the firm operates
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The firm is able to benefit from lower average costs (AC) generated by factors outside of the firm
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Sources of External Economies of Scale
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Explanation |
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Geographic cluster |
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Transport links |
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Skilled labour |
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Favourable legislation |
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Types of Diseconomies of Scale
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As a firm continues to increase its scale of output in the long-run, at some point its long run average cost (LRAC) will start to increase
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The reasons for the increase in the LRAC are called diseconomies of scale
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During this period, the firm is facing decreasing returns to scale
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Causes of Diseconomies of Scale
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Management diseconomy of scale |
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Communication diseconomy of scale |
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Geographical diseconomy of scale |
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Cultural diseconomy of scale |
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Increasing, Constant & Decreasing Returns to Scale
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The minimum efficient scale is the lowest cost point on a long-run average total cost (LRAC) curve
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It represents the lowest possible cost per unit that a firm in the industry can achieve in the long run
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Diagram: Increasing and Decreasing Returns to Scale

Diagram analysis
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In the short-run, the firm operates on its short-run average cost curve
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In the long-run, the firm will increase its capacity (e.g. build a new factory), and then operate for a period of time on a new short-run cost curve
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Each subsequent short-run average cost (SRAC) curve represents growth and an increase in size
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Output increases with each period of growth
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Initially, firms experience increasing returns to scale as a result of the economies of scale
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At a certain level of output, the firm will reach the minimum efficient scale where it experiences constant returns to scale
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If it continues to grow beyond that level of output, the firm will experience decreasing returns to scale as diseconomies of scale occur
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