How do I determine sample sizes for testing controls?
The Guide includes tables to help auditors determine sample sizes in specific situations. The tables use input factors such as risk and expected deviation rates to help an auditor determine how many items should be tested. Sample sizes vary based on differences in the assessment of these factors. Some firms’ audit methodologies include forms that provide guidance to auditors on control testing sample sizes. Those forms incorporate similar statistical theories in determining the sample size. How do I calculate a sample size for controls when the population is small? Often a company’s most important controls — such as bank reconciliations or transactional reviews — do not happen every day.
