Statistical versus Non-Statistical SamplStatistical versus Non-Statistical Sampling Approaches

Statistical versus Non-Statistical Sampling Approaches

32 The decision whether to use a statistical or non-statistical sampling approach is a matter for the auditor’s judgement regarding the most efficient manner to obtain sufficient appropriate audit evidence in the particular circumstances. For example, in the case of tests of controls the auditor’s analysis of the nature and cause of errors will often be more important than the statistical analysis of the mere presence or absence (that is, the count) of errors. In such a situation, non-statistical sampling may be most appropriate.

33 When applying statistical sampling, the sample size can be determined using either probability theory or professional judgement. Moreover, sample size is not a valid criterion to distinguish between statistical and non-statistical approaches. Sample size is a function of factors such as those identified in Appendices 1 and 2. When circumstances are similar, the effect on sample size of factors such as those identified in Appendices 1 and 2 will be similar regardless of whether a statistical or non-statistical approach is chosen.

34 Often, while the approach adopted does not meet the definition of statistical sampling, elements of a statistical approach are used, for example the use of random selection using computer generated random numbers. However, only when the approach adopted has the characteristics of statistical sampling are statistical measurements of sampling risk valid.