Data released by the American petroleum institute (API) showed that U.S. crude oil inventories fell 5.2 million barrels in the week ended Dec. 15, down from an expected 35.18 million barrels. Refinery inventories fell more than expected, while gasoline inventories rose, but were less than expected. The overall API data is good and good for oil prices. 1. Principles of securities investment Activity-based costing (ABC) is an effective management technique for assigning and manipulating the overhead costs. Overhead expense analysis and assignment can be achieved more accurate by utilizing ABC methods for a variety of products, for product expenses and profitability analysis and for appropriate distribution and control over the overheads.