Explanation Rough order of magnitude (ROM) cost estimating is a process of estimating the costs of the proposed solutions with a high level of uncertainty, usually in the range of -25% to +75%. ROM cost estimating is used to compare the feasibility and affordability of different solutions and to support decision making. ROM cost estimating is not a detailed or accurate process, but rather a quick and approximate way of assessing the costs of the solutions. References: CBAP / CCBA Certified Business Analysis Study Guide, Chapter 6: Requirements Analysis, page 202. Certified Business Analysis Professional (CBAP) Handbook, page 6.