Exam IIA-CIA-Part1 topic 6 question 12 discussion

While performing an accounts payable engagement, a senior auditor wants to conduct several tests of controls for travel expenses. Which of the following actions are most appropriate for the senior auditor to undertake?
1. Ensure all tests use a random sampling technique.
2. Consider a judgmental approach for the sample size.
3. Assess testing errors through root cause analysis.
4. Ensure that the entire data set is tested.