Economies and diseconomies of scale — Edexcel A-Level Economics A
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Economies and diseconomies of scale explained
Internal economies of scale are cost advantages a firm gains as its own output rises: buying in bulk lowers average input prices, specialisation and division of labour raise labour productivity, larger plant spreads fixed costs, and marketing or finance costs can be spread over more units, so long-run average cost (LRAC) falls. Internal diseconomies arise when the firm grows too large: coordination, communication and control problems, low staff motivation and industrial relations friction push LRAC up. External economies come from industry growth, such as a shared skilled labour pool, supplier clusters and improved infrastructure, shifting the firm's LRAC curve down; external diseconomies, such as congestion, rising local wages or scarce raw materials, shift it up.
Your focus
- Distinguish internal economies and diseconomies of scale from external economies and diseconomies of scale.
- Explain how each type of economy or diseconomy affects a firm's long-run average cost.
- Apply the concepts to a given scenario to identify the correct cost effect.
Economies and diseconomies of scale exam tips
Marking Points
- Internal economies of scale: cost advantages from the firm's own growth, lowering long-run average cost as output rises.
- Internal diseconomies of scale: cost disadvantages from the firm becoming too large, raising long-run average cost.
- External economies of scale: cost reductions from growth of the whole industry, shifting the firm's LRAC curve downward.
- External diseconomies of scale: cost increases from industry growth, such as congestion or scarce inputs, shifting LRAC upward.
- Correct distinction between internal (firm-specific) and external (industry-wide) sources of cost change.
Examiner Tips
- 💡Read the stem carefully to identify whether the cost change is caused by the firm's own output or by industry growth before selecting an option.
- 💡Eliminate options that describe short-run cost behaviour or fixed costs rather than long-run average cost changes.
- 💡Check the direction of the effect: economies lower LRAC, diseconomies raise it, and external effects shift the whole LRAC curve.
Common Mistakes
- Confusing internal with external economies: internal arise from the individual firm's expansion, while external arise from industry-wide growth; state which agent causes the cost change.
- Treating economies of scale as increasing returns forever: beyond a point, internal diseconomies can raise LRAC, so the LRAC curve is typically U-shaped.
- Assuming external economies lower the firm's own costs only through its own output: they shift the LRAC curve for all firms in the industry regardless of each firm's size.