SAMPLING DALAM PENGUJIAN PENGENDALIAN

AU 350.01 defines audit sampling as the application of an audit procedure to less than 100% of the items within an account balance or class of transactions for the purpose of evaluating some characteristics of the balance or class.

Audit sampling is applicable to both tests of controls and substantive tests. However, it is not equally applicable to all the auditing procedures that may used in performing these tests.

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When sampling is used in meeting the second and third standards of fieldwork, it should be recognized that uncertainties may result from factors:1. Associated directly with the use of sampling (sampling risk) and2. Unrelated to sampling (nonsampling risk).

Sampling risk relates to the possibility that a properly drawn sample may not be representative of the population.

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The risk of assessing control risk too low is the risk that the assessed level of control risk based on the sample supports the planned assessed level of control risk when the true operating effectiveness of the control structure policy or procedure, if known, would not be considered adequate to support the planned assessed level.

The risk of assessing control risk too high is the risk that the assessed level of control risk based on the sample does not support the planned assessed level of control risk when the true operating effectiveness of the control structure policy or procedure, if known, would be considered adequate to support the planned assessed level.

Risiko Sampling dalam Test of ControlRisiko Sampling dalam Test of ControlRisiko Sampling dalam Test of ControlRisiko Sampling dalam Test of Control

The risk of incorrect acceptance is the risk that the sample supports the conclusion that the recorded account balance is not materially misstated when it is materially misstated.

The risk of incorrect rejection is the risk that the sample supports the conclusion that the recorded account balance is materially misstated when it is not materially misstated.

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Nonsampling risk refers to the portion of the audit risk that is not due to examining only a portion of the data. Sources of nonsampling risk include:1.Human mistakes, such as failing to recognize errors in documents,2.Applying auditing procedures inappropriate to the audit objective,3.Misinterpreting the results of a sample, and4.Relying on erroneous information received from another party, such as an erroneous confirmation response.

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An auditor may use sampling to obtain information about many different characteristics of a population. However, most audit samples lead either to an estimate of:1. a deviation rate or2. a dollar amount.

When statistical sampling is used, these sampling techniques are identified as attribute sampling and variables sampling, respectively.

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Attribute Sampling dan Variable Sampling Attribute Sampling dan Variable Sampling Attribute Sampling dan Variable Sampling Attribute Sampling dan Variable Sampling

The steps involved in a nonstatistical sampling plan include the following:1.Determine the audit objectives and procedures to meet the objectives.2.Define the population and sampling unit.3.Specify the control of interest and evidence that the control was effective or ineffective.4.Use professional judgment to determine sample size.5.Use professional judgment to determine the sample selection method.6.Apply audit procedures for tests of controls.7.Evaluate the sample results.

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The steps in a statistical sampling plan for tests of controls are as follows:1. Determine the audit objectives.2. Define the population and sampling unit.3. Specify the attributes of interest.4. Determine the sample size.5. Determine the sample selection method.6. Execute the sampling plan.7. Evaluate the sample results.

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Attributes dalam PengendalianAttributes dalam PengendalianAttributes dalam PengendalianAttributes dalam Pengendalian

In order to determine a sample size for each attribute or control to be tested, the auditor must specify a numerical value for each of the following factors:

1. Risk of assessing control risk too low2. Tolerable deviation rate3. Expected population deviation rate

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When selecting a random sample, it is possible that the same sampling unit may be drawn more than once. When the duplicate number is ignored, the auditor is said to be sampling without replacement.

Statistical tables used by auditors to determine sample size are often based on sampling with replacement. As a practical matter, however, the auditor usually samples without replacement because no new information would be obtained from examining the same item twice.

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Systematic sampling consists of selecting every nth item in the population from one or more random starts. The interval between items is usually referred to as the skip interval.

When a single random start is used, the interval can be calculated by dividing the population size by the sample size.

A major advantage of systematic selection is that it may take less time than other selection methods.

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SAMPLING DALAM PENGUJIAN SUBSTANTIF

Sampling plans for substantive tests may be designed to:1.Obtain evidence that an account balance is not materially misstated or2.Make an independent estimate of some amount.

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Audit sampling in substantive tests is subject to both sampling risk and nonsampling risk. The sampling risks associated with substantive tests are:1.Risk of incorrect acceptance (beta risk) — the risk that the sample supports the conclusion that the recorded account balance is not materially misstated when it is materially misstated.2.Risk of incorrect rejection (alpha risk) — the risk that the sample supports the conclusion that the recorded account balance is materially misstated when it is not materially misstated.

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The following 2 statistical sampling approaches may be used by the auditor in substantive tests:1.Probability-proportional-to -size (PPS) sampling and2.Classical variables sampling.

Pendekatan SamplingPendekatan SamplingPendekatan SamplingPendekatan Sampling

Pendekatan SamplingPendekatan SamplingPendekatan SamplingPendekatan Sampling

Probability-Proportional-to-Size SamplingProbability-Proportional-to-Size SamplingProbability-Proportional-to-Size SamplingProbability-Proportional-to-Size Sampling

PPS sampling is an approach that uses attribute sampling theory to express a conclusion in dollar amounts rather than as a rate of deviations. This form of sampling may be used in substantive tests of both transactions and balances.

Probability-Proportional-to-Size SamplingProbability-Proportional-to-Size SamplingProbability-Proportional-to-Size SamplingProbability-Proportional-to-Size Sampling

The steps in a PPS sampling plan are similar to those used in attribute sampling. The steps are:1. Determine the objectives of the plan2. Define the population and sampling unit3. Determine the sample size4. Determine the sample selection method5. Execute the sampling plan6. Evaluate the sample results

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