Briefly explain five methods of sampling

Auditing and Assurance Revision Questions and Answers

Methods of sampling is presented below:
Haphazard Sampling
Haphazard sampling is a technique adopted by the auditor where the sample does not follow a structured technique. Haphazard sampling is not appropriate when using statistical sampling and the auditor should always ensure that haphazard sampling is not „doctored‟ in such a way that it deliberately avoids sampling items which, for example, are difficult to locate. All items in the population should stand a chance of being sampled.
Stratified Sampling
This is a technique where the auditor will split items in a sample into their various strata‟s. For example, in a payroll sample the auditor might split the sample between full-time males, full-time females, part- time males and part-time females and work out the percentage of the strata in the population (the population being the total amount that makes up a figure). For example if 30% of the population are full- time males, 40% full-time females, 20% part-time males and 10% part-time females, then the sample will consist of 30% full-time males, 40% full-time females etc.
Systematic Sampling
Often referred to as „interval‟ sampling this is where the auditor will take the number of sampling units in the population and divide this into the sample size to give a sampling interval. For example, in a sales invoice sample where the sampling interval is 20, then the auditor will determine a starting point for sampling and sample every 20th sales invoice thereafter.

Block Sampling
Block sampling is a technique where the auditor applies procedures to such items that all occur in the same block of time or sequence. For example, testing amounts received from customers in the month of September. Alternatively, a „block‟ of remittance advice received in September would be tested in their entirety. It is to be noted that block sampling should be used with caution because valid references cannot be made beyond the period or block examined. Where the auditor does use block sampling, then many blocks should be selected to help minimize sampling risk.
Auditors can use their judgement in selecting items for sampling. There are three basic issues which determine which items are selected:
• The value of items
• The relative risk (items prone to error should be given special attention)
• The representatives (the sample should be representative of the population)

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