Control Effectiveness

Control effectiveness is a measure of how well a control reduces the risk it is designed to mitigate. It assesses whether the control is operating as designed, consistently applied, and achieving its intended outcome of reducing likelihood or impact of a risk event.

Control effectiveness is evaluated through control testing — examining whether the control is properly designed (design effectiveness) and operating consistently in practice (operational effectiveness). Effectiveness is typically rated as fully effective, partially effective, or ineffective. The rating directly impacts residual risk calculations: fully effective controls significantly reduce residual risk, while ineffective controls leave residual risk close to inherent risk. Regular control testing ensures that controls continue to operate effectively over time.