원가구조 차이에 의한 사업위험 차이: 레버리지도는 그 적절한 측정치인가?

This study investigates the properties of the degree of total leverage (DTL), the ratio of the change rate of net income over the change rate of sales. DTL is generally perceived as a measure of business risk caused by a cost structure. This paper analyzes the relationship between a cost structure and DTL in a standard Cost-Volume-Profit model with a mixed cost structure. It shows that a firm with high fixed costs and low variable costs does not necessarily have a higher DTL than a firm with low fixed costs and high variable costs. This means the typical explanation in textbooks saying that organizations with a high proportion of fixed costs in their cost structures have high leverage could be misleading. The degree of total(combined) leverage (DTL) is identical to the ratio of the sales volume over the margin of safety (the difference between the sales volume and the break-even point). At the given sales volume, either a higher unit variable cost or a higher fixed cost results in a higher break-even point and a higher DTL. Hence, even with high fixed costs, very low variable costs could make the break-even volume and DTL low. It is shown that DTL is higher when the relative ratio of fixed costs is higher than that of unit contribution margins at the given sales volume. DTL of a firm with the higher fixed costs structure is higher(lower) when the indifference sales volume of two different cost structures (one with high fixed, low variable costs and the other with low fixed, high variable costs) is greater(less) than the break-even volume. The indifference sales volume is defined as a sales volume incurring the same total costs under different cost structures. The degree of total(combined) leverage (DTL) is the combination of the degree of operating leverage (DOL) and the degree of financial leverage (DFL). DOL is the ratio of the change rate of operating income over the change rate of sales. DOL is identical to the ratio of the sales volume over the difference between the sales volume and the operating income break-even point. DOL is higher when the relative ratio of fixed operating costs is higher than that of unit contribution margins at the given sales volume. The degree of financial leverage (DFL) is the ratio of the change rate of net income over the change rate of operating income. DFL is identical to the ratio of the difference between the sales volume and the operating income break-even point over the difference between the sales volume and the break-even point. DFL is higher when the relative ratio of financial fixed costs (interest expenses) is higher than that of operating incomes. Even without difference in financial fixed costs, the difference in operating cost structure could create difference in DFL through the difference in operating incomes. The income variance, a typical risk measure in economics and finance, depends on the unit variable cost, not on the fixed costs. When the unit variable cost is higher at a given fixed costs, DOL is higher but the income variance is lower. Therefore, the two risk measures, the income variance and DOL do not have a positive relationship.