Integrated Business Solutions (Multidisciplinary Case Study with Strategic Management) · Advanced Auditing, Assurance and Professional Ethics

Audit Evidence, Sampling and Analytical Procedures for CA Final

Updated 5 October 2026

Audit evidence is all information an auditor uses to reach conclusions for the opinion. It must be sufficient (quantity) and appropriate (relevance and reliability). You gather it through inspection, observation, confirmation, recalculation, reperformance, analytical procedures and inquiry. Solve questions by identifying the assertion, judging reliability, choosing the procedure, and concluding.

Understand Audit Evidence, Sampling and Analytical Procedures

Your audit opinion is only as good as the evidence behind it. Audit evidence (SA 500) is the information you use to reach conclusions. It includes accounting records and other information. Sufficiency is the quantity of evidence. Appropriateness is its quality, meaning its relevance and reliability. Higher risk of misstatement needs more evidence. Better quality evidence reduces the quantity needed, but poor quality evidence cannot be fixed by getting more of it.

Reliability depends on the source and nature. In general, evidence is more reliable when it comes from independent external sources, when internal controls over it are effective, when you obtain it directly rather than by inference, when it is in documentary form, and when it is an original rather than a photocopy or fax. Use these as general guides, not absolute rules.

You cannot test everything, so you use audit sampling (SA 530): applying procedures to less than 100% of items in a population so that every sampling unit has a chance of selection. You then conclude about the whole population. Sampling risk is the risk that your conclusion from the sample differs from the one you would reach by testing everything. Non-sampling risk arises from wrong procedures or misreading evidence. Statistical sampling uses random selection and probability theory to evaluate results. Anything else is non-statistical sampling. Both can give sufficient evidence if designed properly.

Analytical procedures (SA 520) evaluate financial information by studying plausible relationships between financial and non-financial data. SA 520 requires them in the overall review near the end of the audit. SA 315 (Revised) requires them as part of risk assessment procedures. As substantive procedures they are optional. If you find fluctuations or relationships inconsistent with other information, or that differ from expected values, you investigate by inquiring of management and obtaining appropriate evidence.

Other evidence sources are tested by their own standards. External confirmations (SA 505) are direct responses from third parties. Auditor's expert and management's expert issues sit in SA 620 and SA 500. Accounting estimates (SA 540) need you to assess the method, data and assumptions. Written representations (SA 580) are management's formal statements. They support other evidence but never replace it.

Key rules to remember

Audit evidence: Audit evidence = Sufficiency (quantity) + Appropriateness (relevance + reliability); Risk of misstatement drives quantity. Quality of evidence cannot be offset by quantity alone.
Audit procedures to obtain evidence: Inspection, Observation, External confirmation, Recalculation, Reperformance, Analytical procedures, Inquiry; Inquiry alone is normally not sufficient to test operating effectiveness of controls or to detect a material misstatement.
Performance materiality: Performance materiality = an amount set below materiality for the financial statements as a whole (SA 320); It is set to reduce to an appropriately low level the probability that uncorrected and undetected misstatements in aggregate exceed materiality for the financial statements as a whole.
Tolerable misstatement and sample: Tolerable misstatement = application of performance materiality to a sampling procedure, set at an amount not exceeding performance materiality; SA 530 defines it as a monetary amount set by the auditor for which the auditor seeks an appropriate level of assurance that it is not exceeded by the actual misstatement in the population. It may be equal to or lower than performance materiality, but should not exceed it. SA 530 requires you to consider it when designing the sample.
Projected misstatement: Projected misstatement = (Misstatement found in sample ÷ Sample value) × Population value; This is a ratio projection. It is one common method for monetary values. The projection already includes the misstatement found in the sample. If management corrects the misstatements found, the projected misstatement in the items not tested still remains. If a misstatement is established as an anomaly, it may be excluded from the projection, but you must still consider its effect along with the projected misstatement of the non-anomalous part of the population. Compare the result with tolerable misstatement.
Anomaly: Anomaly = misstatement demonstrably not representative of the population; Only exclude it from projection if you obtain a high degree of certainty that it is an isolated occurrence. Even then, consider its effect along with the projected misstatement of the rest of the population.
Statistical sampling features: Random selection + probability theory to evaluate results and measure sampling risk; If either feature is missing, the approach is non-statistical.
Analytical procedure threshold: Investigate differences exceeding the amount of difference from expected value that is acceptable; Set the acceptable difference using the assurance you need and the precision of your expectation.
Written representation reliance: Written representations are necessary but not sufficient evidence; They do not replace other evidence about any matter.

How to solve Audit Evidence, Sampling and Analytical Procedures questions

Use this method for any case or descriptive question on evidence, sampling, analytical procedures, confirmations, estimates or representations.

1Identify the assertion or account balance and the risk involved, such as existence of inventory or completeness of liabilities.
2Name the governing standard: SA 500 (evidence), SA 530 (sampling), SA 520 (analytical), SA 505 (confirmations), SA 540 (estimates), SA 580 (representations).
3Judge the reliability of the evidence in the case by source, form, directness and controls.
4Choose or critique the procedure and say whether it addresses the assertion. State if more evidence is needed.
5Apply the rule to the facts: sample design, expectation and threshold, confirmation follow-up, or representation refusal.
6Give the consequence for the audit: extend procedures, modify the opinion, consider reliability of management, or withdraw.
7Write the answer in provision, facts, conclusion order. Keep each point to one clear sentence.

Quickest way: Source-Assertion-Standard check

When to use it: Use this for case-scenario MCQs where you have about 90 seconds per question.

Read the last line first to see whether the question asks about sufficiency, reliability, sampling or a representation.
Underline the source of evidence: external, internal, oral or written.
Match to the standard and recall its one key rule, such as: if management does not provide the representations on its responsibilities (including that it has given the auditor all relevant information and access), or doubt about management's integrity makes those representations unreliable, the auditor disclaims an opinion under SA 705 (Revised), after discussing with management and re-evaluating integrity. For any other refused representation, discuss with management, re-evaluate integrity and the reliability of other evidence, and take appropriate action including the effect on the opinion under SA 705 (Revised).
Eliminate options that say a procedure is always enough, or that representations or inquiry alone suffice.
Pick the option that adds corroborating evidence or investigates the exception.

Common mistakes in Audit Evidence, Sampling and Analytical Procedures

Treating sufficiency and appropriateness as the same thing.
Both sound like 'enough evidence', so students use them interchangeably.
Fix: Sufficiency is quantity. Appropriateness is quality (relevance and reliability). Say that more of poor evidence does not cure poor quality.
Saying written representations can replace other audit evidence.
Signed management statements look authoritative.
Fix: State that representations are necessary but do not provide sufficient appropriate evidence on their own on any matter.
Calling any sample with judgment a non-statistical sample, or any random sample statistical.
Students focus on how items were picked and ignore evaluation.
Fix: Statistical needs both random selection and probability theory to evaluate results. If either is missing, it is non-statistical.
Ignoring a misstatement in the sample as an 'error' and not projecting it.
Students think a small sample misstatement is immaterial.
Fix: Project misstatements to the population, except genuine anomalies, and compare with tolerable misstatement.
Saying analytical procedures are mandatory at every stage.
They appear in several standards, which blurs the stages.
Fix: SA 315 (Revised) requires them as risk assessment procedures and SA 520 requires them in the overall review near the end of the audit. As substantive procedures they are a choice.
Accepting a confirmation reply that came through the client or ignoring non-response.
Students focus on getting a reply and not on control over the process.
Fix: Keep control of selection, sending and receipt. If there is no reply, perform alternative procedures. Consider reliability concerns on replies received.

Worked examples

Example 1

ABC Ltd has trade receivables of ₹4,00,00,000. The auditor selects a sample of receivables worth ₹40,00,000 using random selection and finds misstatements of ₹1,20,000 in the sample. Performance materiality is ₹6,00,000. The auditor sets tolerable misstatement for this test at an amount not exceeding performance materiality; for illustration, assume it is set equal to it at ₹6,00,000. No anomalies are identified. What should the auditor conclude?

Show the solution

Provision: SA 530 requires you to project sample misstatements to the population and compare with tolerable misstatement. It also requires you to investigate the nature and cause of the misstatements found. Tolerable misstatement is set at or below performance materiality. Here it is assumed equal to it for illustration.
Ratio of misstatement in sample = ₹1,20,000 ÷ ₹40,00,000 = 3%.
Projected misstatement = 3% × ₹4,00,00,000 = ₹12,00,000. This already includes the ₹1,20,000 found in the sample.
Compare: ₹12,00,000 exceeds tolerable misstatement of ₹6,00,000.
Even if management corrects the ₹1,20,000 found, the projected misstatement in the untested items remains: 3% × ₹3,60,00,000 = ₹10,80,000, which is also above ₹6,00,000.
Conclusion: the sample does not provide a reasonable basis for conclusions about the population tested. The auditor should investigate the nature and cause of the misstatements and consider their effect on the audit objective of the test and on other areas of the audit. The auditor should also consider extending testing or performing additional procedures, request management to investigate and correct the identified misstatements of ₹1,20,000, and evaluate the effect on the audit opinion.

Answer: Projected misstatement is ₹12,00,000, which is above the assumed tolerable misstatement of ₹6,00,000, so the sample does not provide a reasonable basis for conclusions on the population. Correcting the ₹1,20,000 found does not remove the ₹10,80,000 projected for the untested items. The auditor should investigate the nature and cause of the misstatements and consider their effect on the audit objective and other areas of the audit. The auditor should also consider extending testing or performing additional procedures, request management to investigate and correct the identified misstatements, and evaluate the effect on the audit opinion.

Example 2

During the audit of XYZ Ltd, management refuses to provide the written representation the auditor requested that it has fulfilled its responsibility to provide the auditor with all relevant information and access, that is, completeness of information provided. What is the auditor's course of action?

Show the solution

Provision: SA 580 says representations are necessary but do not by themselves give sufficient appropriate evidence.
Facts: management has refused the representation that it has provided the auditor with all relevant information and access. This is a representation on management's responsibilities.
First, discuss the matter with management. Re-evaluate management's integrity and consider the effect on the reliability of other representations and other audit evidence.
Take appropriate action, including determining the possible effect on the opinion under SA 705 (Revised).
Distinguish the two cases. If management does not provide the representations on its responsibilities (for the financial statements, or for providing information and access), or the auditor concludes there is sufficient doubt about management's integrity so that these representations are unreliable, the auditor disclaims an opinion under SA 705 (Revised). If management refuses any other representation, the auditor discusses it with management, re-evaluates integrity and the reliability of other evidence, and takes appropriate action, including determining the possible effect on the opinion under SA 705 (Revised). A disclaimer does not follow automatically in that case.
Conclusion: here the refused representation is on management's responsibilities, so after the discussion and the re-evaluation of integrity, the auditor disclaims an opinion on the financial statements under SA 705 (Revised). Having obtained other records does not change this outcome.

Answer: The auditor should first discuss the refusal with management and re-evaluate management's integrity and the reliability of other representations and evidence. If management does not provide the representations on its responsibilities, including that it has given the auditor all relevant information and access, or there is sufficient doubt about management's integrity, the auditor disclaims an opinion under SA 705 (Revised). Refusal of any other representation requires the auditor to discuss with management, re-evaluate integrity and the reliability of other evidence, and take appropriate action, including determining the possible effect on the opinion under SA 705 (Revised). As the refusal here concerns management's responsibilities, the auditor disclaims an opinion.

Exam tips

In case MCQs, look for words like 'only', 'always' and 'sufficient'. Representations or inquiry alone are rarely the right answer.
For sampling questions, show the projection working and compare it with tolerable misstatement before concluding.
Answer descriptive questions in provision, facts, conclusion format and name the SA number where you are sure of it.
For analytical procedure cases, state the expectation, the acceptable difference, the investigation and the corroborating evidence.
In Paper 6 open-book cases, link evidence to the audit risk and the opinion consequence rather than just reciting the standard.

Practice questions from Advanced Auditing, Assurance and Professional Ethics

Audit Evidence, Sampling and Analytical Procedures: frequently asked questions

What is the difference between statistical and non-statistical sampling?

Statistical sampling uses random selection and probability theory to evaluate results, including measuring sampling risk. Any approach that lacks one of these is non-statistical. Both can give sufficient appropriate evidence if properly designed.

Are analytical procedures mandatory in every audit?

SA 315 (Revised) requires them as part of risk assessment procedures, and SA 520 requires them in the overall review near the end of the audit. Using them as substantive procedures is a choice the auditor makes based on the assertion and risk.

Can written representations replace other audit evidence?

No. Under SA 580 they are necessary evidence but do not provide sufficient appropriate evidence on their own about any matter. They also do not affect the nature or extent of other evidence you must obtain.

What is sampling risk and non-sampling risk?

Sampling risk is the risk that the conclusion from a sample differs from the conclusion if the whole population were tested. Non-sampling risk comes from other causes, such as using an inappropriate procedure or misinterpreting evidence.