The most helpful thing for an IS auditor when assessing the effectiveness of controls is the results of control testing, as this provides objective and reliable evidence of how well the controls are designed and operating in practice. A control self-assessment (CSA) is a technique that involves the participation of process owners and stakeholders in evaluating the effectiveness of controls, but it may not be as rigorous or independent as control testing. Interviews with management are useful for gaining an understanding of the control environment and culture, but they may not reflect the actual performance of controls. A control matrix is a tool that maps the controls to the objectives, risks, and requirements, but it does not measure the effectiveness of controls. References: CISA Review Manual (Digital Version), Chapter 1: Information Systems Auditing Process, Section 1.3: IT Audit Process