📖 What is Sampling?
Sampling is an audit procedure applying procedures to less than the entire population of items. It’s used to gather sufficient appropriate audit evidence when testing large volumes of data. Sampling allows auditors to form conclusions about the population without examining every item individually.
"Statistical versus non-statistical sampling is a frequent exam topic. Statistical sampling uses objective selection criteria and allows for quantifiable conclusions. Non-statistical sampling relies on auditor judgment and requires careful documentation of rationale. Understand the implications of sample size and selection method."
📚 Certification: Certified Information Systems Auditor (CISA)
🔑 What are the Key Concepts of Sampling?
- ▸ Statistical sampling uses random selection and quantifiable measures like sampling error to evaluate results, providing objective conclusions.
- ▸ Non-statistical sampling relies on auditor judgment to select items, requiring thorough documentation of the rationale for selection.
- ▸ Sample size is crucial; a larger sample generally provides more reliable results, but also increases audit effort and cost.
- ▸ Sampling risk is the possibility that the sample does not accurately represent the population, leading to incorrect audit conclusions.
- ▸ Attribute sampling focuses on the presence or absence of characteristics, while variables sampling measures numerical values.
🎯 How does Sampling appear on the CISA Exam?
You may be asked to identify the appropriate sampling method (statistical vs. non-statistical) given a specific audit objective and population size.
A scenario might describe an auditor discovering errors in a sample; expect questions about how this impacts the auditor’s conclusion regarding the entire population.
Expect questions about calculating sample size using statistical formulas or interpreting the results of statistical sampling tests.
❓ Frequently Asked Questions
When is non-statistical sampling acceptable?
Non-statistical sampling is often used for tests of controls where the auditor is assessing whether a control is operating effectively, and documentation is key to support the auditor’s judgment.
How does sampling risk affect the audit?
Sampling risk means the auditor might reach an incorrect conclusion about the population. Increasing sample size or using statistical sampling can help mitigate this risk, but cannot eliminate it entirely.
What’s the difference between tolerable error and sampling error?
Tolerable error is the maximum error an auditor is willing to accept, while sampling error is the difference between the sample results and the true population value. The auditor sets the tolerable error.