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Choose your confidence level, tolerable and expected rates, and get the sample size. Then draw the items with a seed so the same selection can be reproduced in your working papers.
Exact binomial method for a large population. If the sample finds more than 0 deviation(s), the control cannot be relied on at this tolerable rate and confidence.
Pyalm Books gives you the evidence an auditor asks for in one place — a double-entry ledger, manual journals, period locking, bank reconciliation, receivables ageing and VAT returns. Free while in beta.
When you test whether a control operated (an approval, a three-way match), the question is the deviation rate. The sample size is the smallest n for which finding no more than the expected number of deviations gives the stated confidence that the true rate is below your tolerable rate. For 95% confidence, a 5% tolerable rate and zero expected deviations that is 59 items.
For substantive testing of balances such as receivables, MUS treats every currency unit as a sampling unit, so larger items are more likely to be selected. Sample size is book value times a reliability factor, divided by tolerable misstatement less expected misstatement times an expansion factor. The sampling interval is book value divided by sample size.
📖 Read the full guide: Audit Sampling Explained: Attribute Sampling & MUS
Overall, performance and clearly trivial materiality from a benchmark and percentage.
Test a ledger for unnatural first-digit patterns — with chi-square, MAD and per-digit z-scores.
Spot repeated payments and invoices by amount, date, vendor and reference.
It uses the exact binomial probability, which closely tracks published tables; differences of one or two items are normal because tables round and use slightly different conventions. Check your firm's methodology if you must match a specific table.
If you expect deviations at or above the tolerable rate, no sample size can support reliance on the control. Reassess the control or move to substantive procedures.
A seed makes the random draw repeatable. Record it with the population size and sample size so a reviewer can regenerate exactly the same items.
No. It supports the mechanics of ISA 530 sampling. Population definition, stratification, tolerable rate and evaluating the results remain judgements for the auditor.
