Sampling in a Performance Audit Context

Sampling is a methodology used for a variety of purposes in different professions, from ecological studies to surveys of political opinions. Some general concepts are relevant for all users of sampling methodology, but each discipline also uses sampling in its own specific way, and performance auditing is no exception. This section presents a short introduction to sampling in a performance audit context.

What Is Sampling and Why Is It Important When Conducting an Audit?

Essentially, sampling is the selection of a subset of the totality of elements that could be analyzed, called the population. It is a useful tool whenever assessing the whole population (which is called performing a census) is not efficient or insights regarding the nature or cause of a problem are required.

Although performing a census is more and more facilitated by computer-assisted audit techniques, there are still plenty of situations in which auditors must use sampling to obtain information that will allow them to conclude on their audit objective. The sample is therefore of critical importance to auditors because it provides the basis for their analysis and findings. For example, in the Office of the Auditor General of Canada’s 2018 reports, 7 of the 14 performance audits conducted that year used sampling to draw audit observations.

When files are mostly paper-based or when electronic files and data are not amenable to data analytics, sampling uses resources more efficiently and takes less time than performing a census (which would be unrealistic in most circumstances). Depending on the type of sampling approach used, it may also be possible to extrapolate the findings of the analysis to the whole population.

Knowing how to design an appropriate sampling methodology is a useful skill for performance auditors. It is not uncommon for larger audit institutions to have one or more sampling experts on staff. Regardless, it is advantageous for all performance auditors to have at least a basic understanding of sampling approaches and methods and how to apply them. At a minimum, having this knowledge can enable auditors to implement less complex sampling methods and collaborate with external sampling experts who may be consulted on occasional projects.

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