Explain commonly used methods to be used by auditor in selection of audit sample.

While there are a number of selection methods, three methods commonly used are: Random Selection: This method ensures that all items in the population have an equal chance of selection, for example, by use of random number tables. Systematic Selection: This method involves selecting items using a constant interval between selections, the first interval having a random start. The interval might be based on a certain number of items (for example, every 20th voucher number) or on monetary totals (for example, every ₹1,000 increase in the cumulative value of the population). When using systematic selection, the auditor would need to determine that the population is not structured in such a manner that the sampling interval corresponds with a particular pattern in the population. Haphazard selection: This is an acceptable alternative to random selection, provided the auditor attempts to draw a representative sample from the entire population with no intention to either include or exclude specific units. When the auditor uses this method, care needs to be taken to guard against making a selection that is biased, for example, towards items which are easily located, as they may not be representative.