The chief audit executive was asked to define me internal audit activity s key performance...

A key performance indicator (KPI) that measures effectiveness reflects how well the internal audit activity achieves its objectives and meets stakeholder expectations. Post-engagement surveys completed by management, indicating a "meets or exceeds expectations" rating, directly measure the perceived value and impact of the audit work. This KPI shows whether the internal audit function is providing useful insights, recommendations, and assurance that align with management’s needs and expectations, thus demonstrating the effectiveness of the audit activity.

Institute of Internal Auditors (IIA), Practice Guide – Measuring Internal Audit Effectiveness and Efficiency.