4-1 What are the three common approaches for assigning overhead costs to products? 4-2 Why does activity-based costing appeal to some companies? 4-3 Why do departmental overhead rates sometimes result in inaccurate product costs? 4.4 What are the four hierarchical levels of activity discussed in the chapter? 4-5 Why is activity-based costing described as a "two-stage" costing method? 4-6 Why do overhead costs often shift from high-volume products to low-volume products when a company switches from a conventional costing method to activity-based costing? 4-7 What are the three major ways in which activity-based costing improves the accuracy of product costs? 4-8 What are the major limitations of activity-based costing