When addressing excessive overtime being paid to employees in an organization's customer service call center, the most relevant techniques for the internal auditor to use would be trend analysis, external benchmarking, and internal benchmarking. Trend analysis helps in identifying patterns over time, which can highlight the causes of excessive overtime. External benchmarking compares the organization's overtime data with industry standards to identify discrepancies. Internal benchmarking compares overtime across different departments or similar call centers within the organization to identify best practices and areas needing improvement. Confirmation is not as relevant in this context as it is primarily used to verify the accuracy of information through direct verification. References:

The IIA’s Practice Guide on Data Analytics.

The IIA’s International Standards for the Professional Practice of Internal Auditing (Standards), Standard 2320 - Analysis and Evaluation.