What is the most effective approach for an IS auditor to evaluate the control design effectiveness of an automated billing process?

The most effective approach for an IS auditor to evaluate the control design effectiveness of an automated billing process is to conduct a walk-through. A walk-through involves tracing a transaction through the entire billing process, following the flow of data and understanding how controls are implemented at each stage. This method allows the auditor to see firsthand how the system operates, verify that controls are designed as intended, and assess whether they are effectively in place.

By performing a walk-through, the auditor can identify any potential gaps or weaknesses in the control design. It provides a comprehensive understanding of the system's workings and enables the auditor to evaluate whether the controls will function correctly in a real-world scenario. This practical application makes the walk-through one of the most effective methods for assessing control design effectiveness in complex automated processes.

While interviews, inquiries, and reperformance can provide valuable insights, they often lack the depth and detail provided by a walk-through. Interviews may rely on subjective responses from personnel, inquiries could miss nuances in the process, and reperformance focuses on testing already established controls rather than assessing the design and implementation stage. Consequently, a walk-through stands out as the approach that best combines thoroughness and real-world application for evaluating control design effectiveness.