CA Inter Auditing & Ethics – Chapter 3 Notes (Part 1)

SA 530 – Audit Sampling (Concepts, Meaning, Population & Sampling Approaches)

SA 530 – Audit Sampling

Meaning of Audit Sampling

Definition (ICAI)

Audit Sampling means applying audit procedures to less than 100% of items in a population so that every sampling unit has an equal chance of selection, enabling the auditor to draw conclusions about the entire population.

Objective

To provide a reasonable basis for drawing conclusions about the population without checking every transaction.

Why is Audit Sampling Used?

Earlier auditors checked every transaction.

Today, due to:

Effective Internal Controls
Huge volume of transactions
Time constraints
Cost considerations

auditors perform sample checking instead of checking every transaction.

Benefits

Saves time
Reduces audit cost
Efficient
Scientifically reliable (when statistical sampling is used)
Still provides sufficient audit evidence

Scope of SA 530

Applicable when auditor decides to use sampling while performing audit procedures.

It covers:

Statistical Sampling
Non-statistical Sampling
Sample Design
Sample Selection
Sample Evaluation
Sampling Risk

It complements SA 500 – Audit Evidence.

Important Definitions

Population

Entire set of data from which sample is selected.

Example:

Trade Receivables = ₹5 crore

Entire receivable ledger = Population.

Sampling Unit

Individual item selected from the population.

Example

Population → 5,000 Sales Invoices

Sampling Unit → Invoice No. 4523

Relationship

			
Population
      ↓
Sampling Units
      ↓
Sample Selected
      ↓
Audit Procedures
      ↓
Conclusion
      ↓
Applied to Whole Population

		

Characteristics of Population

The population should satisfy 3 conditions.

1. Appropriate

Population should be relevant to the audit objective.

Example

Testing Overstatement of Receivables

Population:

✔ Accounts Receivable Ledger

Testing Understatement of Payables

Population:

✔ Supplier Statements
✔ Unpaid Invoices

NOT Accounts Payable Ledger.

2. Complete

Population should contain all relevant items.

Incomplete population → Wrong conclusion.

Example

Testing sales for whole year

Population should include sales from April to March, not only April–December.

3. Reliable

Population should be:

Accurate
Complete
From reliable source

Otherwise sample becomes unreliable.

Exam Mnemonic

Population = A C R

A → Appropriate

C → Complete

R → Reliable

Representative Sample

Sample selected must represent the characteristics of the whole population.

Representative sample ensures:

Fair conclusion
Less bias
Reliable audit opinion

Types (Approaches) of Sampling

Two approaches:

			
Audit Sampling
      │
 ┌────┴────┐
 │         │
Statistical Non-statistical
Sampling    Sampling

		

Statistical Sampling

Meaning

A sampling approach involving:

Random selection
Probability theory
Measurement of sampling risk

It is scientific and objective.

Characteristics

✔ Random Selection

✔ Mathematical Method

✔ Probability Theory

✔ Sampling Risk Measured

✔ No Auditor Bias

Advantages

Scientific
Objective
Reliable
Less personal bias
Better for large organisations
Suitable for huge transactions

Examples

Trade Receivable Confirmation
Payroll Audit
Purchase Verification
Invoice Testing
Petty Cash Checking

Non-Statistical Sampling

Meaning

Sample selected using:

Auditor’s experience
Professional judgement
Personal knowledge

No probability theory involved.

Examples

Checking:

Highest value invoices
March transactions
Year-end transactions
Top 20 customers

Advantages

Easy
Flexible
Less complicated
Suitable for small audits

Disadvantages

Personal bias
Not scientific
Sampling risk cannot be measured
Less reliable than statistical sampling

Comparison

Basis	Statistical Sampling	Non-Statistical Sampling
Selection	Random	Auditor Judgment
Scientific	Yes	No
Probability Theory	Yes	No
Personal Bias	Nil	Possible
Reliability	High	Moderate
Suitable for	Large Audits	Small Audits

Sampling vs Traditional Audit

Traditional Audit	Audit Sampling
Checks 100% transactions	Checks selected items
Time consuming	Time saving
Costly	Economical
Less efficient	More efficient
Suitable for small population	Suitable for large population

Factors Affecting Extent of Sampling

Auditor considers:

Size of organisation
Internal control system
Reliability of records
Tolerable error
Desired confidence level

CA Exam Keywords ⭐

Audit Sampling
Population
Sampling Unit
Representative Sample
Statistical Sampling
Non-statistical Sampling
Random Selection
Probability Theory
Professional Judgment
Sampling Risk
Tolerable Error
Desired Confidence Level

One-Page Revision Sheet

			
SA 530 – Audit Sampling
Purpose
↓
Check Less than 100%
↓
Draw Conclusion on Population
Population
↓
Appropriate
Complete
Reliable
Sampling Unit
↓
Individual Item
Approaches
1. Statistical
• Random
• Scientific
• Probability
• No Bias
2. Non-statistical
• Auditor Judgment
• Experience
• Simple
• Personal Bias
Representative Sample
↓
Reliable Audit Opinion
Mnemonic:
Population = ACR
(A) Appropriate
(C) Complete
(R) Reliable

		

This completes Part 1 of the notes on SA 530 – Audit Sampling (Concepts & Sampling Approaches).