Certified Information Systems Auditor (CISA) — Question 254

A bank has a combination of corporate customer accounts (higher monetary value) and small business accounts (lower monetary value) as part of online banking. Which of the following is the BEST sampling approach for an IS auditor to use for these accounts?

Answer options

• A. Unstratified mean per unit sampling
• B. Stratified mean per unit sampling
• C. Customer unit sampling
• D. Difference estimation sampling

Correct answer: B

Explanation

Stratified mean per unit sampling is the best approach because it allows the auditor to separately analyze different strata of accounts based on their value, ensuring a more accurate representation of the overall population. Unstratified mean per unit sampling does not account for the variations in account sizes, while customer unit sampling and difference estimation sampling are less effective for capturing the nuances between high and low-value accounts.