The production level at which the long-run average cost curve flattens out is called the minimum efficient scale. (Since the business is able to adjust all factors of production in the long run, it ca...The production level at which the long-run average cost curve flattens out is called the minimum efficient scale. (Since the business is able to adjust all factors of production in the long run, it can effectively rescale the entire operation, so the target production level is sometimes called the scale of the business.) In competitive seller markets, the ability of a firm to achieve minimum efficient scale is crucial to its survival.