• While sampling is not required to test many types of controls, firms replied that sampling is frequently used for tests that involve inspection or re-performance of manual controls, but is less frequently used to test controls that operate at the entity level or those that are automated. When deciding to use sampling in tests of controls, auditors choose between statistical or nonstatistical sampling approaches. According to auditing standards, auditors selecting a nonstatistical approach should arrive at a sample size that is ''comparable to the sample size resulting from an efficient and effectively designed statistical sample, considering the same sampling parameters'' (AICPA 2011, 530.A14; PCAOB 2003, 350.23). While either method is acceptable under auditing standards, statistical sampling requires a statistically acceptable selection method (i.e., random selection, but not haphazard selection) and allows the auditor to quantify sampling risk in evaluating the results of testing. Our study reports an equal division among the six participating firms' approaches in this regard. Based on survey responses, firm guidelines appear to either explicitly require the use of statistical methods or, when nonstatistical methods are permitted, include guidance based on the statistical theory that results in these methods arriving at a sample size and conclusion similar to what would have been reached using a statistical method.Our survey did not address why a firm chose to use a statistical or nonstatistical approach." (Page 9)

Question

Based on the advantages and disadvantages of statistical vs nonstatistical methods, why do you think the firms chose the method they did if they both are supposed to yield the same sample size?