Audit Sampling Prepared by Murodullo Turdiyev. Group Hba-81i Learning Objectives

Selecting the sample

• To draw conclusions about population or strata, the sample needs to be typical of characteristics of population or strata.
• Sample needs to be selected without bias so that all sampling units in the population or strata have a chance of selection.
• Common sampling techniques are:
• Random selection — random number generation
• Systematic selection
• Haphazard selection — select without conscious bias

Steps in systematic selection

For example, suppose the sample size is 20 and

the number of items in the population is 10 000:

• Step 1: Calculate the sample interval:
• Step 2: Give every item in population chance of selection by choosing a random number (random start) within range of 1 and sampling interval (in this example, 500), e.g. 217.
• Step 3: Continue to add sampling interval to random start, and identify items to be sampled, e.g. item nos. 217, 717, 1217. . . 9217, 9717.

Sampling for tests of controls, attribute sampling

• Audit sampling is useful for tests of controls, especially involving inspection of source documentation for specific attributes such as evidence of authorisation (attribute sampling).
• Involves examination of documents for particular attributes related to controls (e.g. authorisation).
• Results of attribute sampling can be used to support or refute an initial assessment of control risk.

Planning and designing sample for tests of controls

• Auditor should consider:
• Audit objectives (assertions of audit interest)
• Tolerable error — maximum error rate that would still support control risk assessment
• Allowable risk of over-reliance — allowable risk of assessing control risk too low
• Expected error — amount of error the auditor expects to find in the population

Reliability factors for assessing required confidence level