§ 80.127
Sample size guidelines.
In performing the attest engagement, the auditor shall sample relevant populations to which agreed-upon procedures will be applied using the methods specified in this section, which shall constitute a representative sample.
(a) Sample items shall be selected in such a way as to comprise a simple random sample of each relevant population; and
(b) Sample size shall be determined using one of the following options:
(1) Option 1. Determine the sample size using the following table:
Sample Size, Based Upon Population Size
No. in population (N)
Sample size
66 and larger
29
41-65
25
26-40
20
0-25
N or 19, whichever is smaller.
(2) Option 2. Determine the sample size in such a manner that the sample size is equal to that which would result by using the following parameters and standard statistical methodologies:
Confidence Level—95%
Expected Error Rate—0%
Maximum Tolerable Error Rate—10%
(3) Option 3. The auditor may use some other form of sample selection and/or some other method to determine the sample size, provided that the resulting sample affords equal or better strength of inference and freedom from bias (as compared with paragraphs (b)(1) and (2) of this section), and that the auditor summarizes the substitute methods and clearly demonstrates their equivalence in the final report on the audit.