Certified Internal Auditor (CIA) Part 2: Practice of Internal Auditing — Question 97

An internal auditor is testing the success of the IT support department in meeting the service levels guaranteed to small, medium, and large customers. The customer's size classification is based on its annual expenditures with the organization and the nature and extent of services it receives. Which of the following sampling techniques would be the most suitable to select customers for this test?

Answer options

• A. Cluster sampling.
• B. Interval sampling.
• C. Stop-and-go sampling.
• D. Stratified sampling.

Correct answer: D

Explanation

Stratified sampling is the correct choice because it allows the auditor to ensure that each customer group (small, medium, large) is adequately represented based on their spending and service level. Cluster sampling, interval sampling, and stop-and-go sampling do not effectively account for the specific customer classifications needed for this assessment.