迈克尔版本微观经济学 第十一章 Chapter11_SM.ppt

* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * 13 sweaters a day cost $9.50 each on ATC4. Long-Run Cost 13 sweaters a day cost $6.80 each on ATC2. The least-cost way of producing 13 sweaters a day. Long-Run Cost Long-Run Average Cost Curve The long-run average cost curve is the relationship between the lowest attainable average total cost and output when both the plant and labour are varied. The long-run average cost curve is a planning curve that tells the firm the plant that minimizes the cost of producing a given output range. Once the firm has chosen its plant, the firm incurs the costs that correspond to the ATC curve for that plant. Long-Run Cost Figure 11.8 illustrates the long-run average cost (LRAC) curve. Long-Run Cost Economies and Diseconomies of Scale Economies of scale are features of a firm’s technology that lead to falling long-run average cost as output increases. Diseconomies of scale are features of a firm’s technology that lead to rising long-run average cost as output increases. Constant returns to scale are features of a firm’s technology that lead to constant long-run average cost as output increases. Long-Run Cost Figure 11.8 illustrates economies and diseconomies of scale. Long-Run Cost Minimum Efficient Scale A firm experiences economies of scale up to some output level. Beyond that output level, it moves into constant returns to scale or diseconomies of scale. Minimum efficient scale is the smallest quantity of output at which the long-run average cost reaches its lowest level. If the long-run average cost curve is U-shaped, the minimum point identifies the minimum efficient scale output level. Long-Run Cost * * The big picture A firm’s production costs depend on the freedom to choose all inputs. In short run, there is less flexibility in terms of choosing the quantity of inputs. Many inputs particularly firm’s plant is fixed in the short run. Firms need time to buy new plants or sell off the existing ones