Auditing standards differ for public and private companies. Public companies must follow the Public Company Accounting Oversight Board (PCAOB) standards, which emphasize strict oversight and detailed documentation. Private companies, however, follow standards set by the AICPA (American Institute of Certified Public Accountants) through the Statements on Auditing Standards (SAS), which offer more flexibility based on risk and size.

Audit sampling is applied under both standards but may vary in rigor. PCAOB standards often require larger sample sizes and more detailed procedures due to the higher expectations for public company transparency.

Practical Example:
For a public company audit under PCAOB rules, an auditor may sample 300 revenue transactions for compliance and accuracy. For a private company of similar size, using AICPA standards, the auditor might sample 150, adjusting for risk and complexity.

Regardless of the standard, audit sampling ensures efficiency and provides reliable audit evidence to support opinions.