The best measure of the impact of business interruptions caused by an IT service outage is the sustained financial loss. This is the amount of money that the enterprise loses due to the disruption of its normal operations, such as lost revenue, increased expenses, or reduced profits. Sustained financial loss reflects the extent and severity of the business interruption, and theeffect on the enterprise’s objectives and performance. Sustained financial loss also helps to determine the recovery objectives and priorities, and to justify the investment in risk mitigation and business continuity strategies. References = Risk and Information Systems Control Study Manual, 7th Edition, Chapter 2, Section 2.2.2, page 691