8 Factors that Influence Sample Size

Multiple factors can influence a sample size, including:

(i) The nature of control – larger samples imply that the auditor should test manual controls because they are subject to less consistency, smaller sampling implies that the auditor is checking automated controls.

(ii) Frequency of operations – larger samples imply that every transaction should be checked, smaller sampling implies that the operation of control happens less frequently.

(iii) Importance of the control – these tests are more important should they be tested more extensively, smaller sampling implies tests are less important.

(iv) Risk of assessing control risk too low – smaller amounts of sampling can result in larger sample size, larger amounts of sampling risk can result in smaller sample size.

(v) Tolerable deviation rate – larger samples imply that the smaller the rate of deviation from the prescribed control procedure, the larger the sample size, while the larger the rate of deviation, the smaller the sample size.

(vi) Expected population deviation rate – larger samples imply that the closer tolerable deviation rate and expected deviation rate are to one another, the larger the sample size, the greater the amount between tolerable deviation rate and expected deviation rate, the smaller the sample size.

(vii) Population size below 5,000 (direct) – the larger the population, the larger the sample rate, the smaller the population, the smaller the sample rate.

(viii) Population size below 5,000 (no effect) – population size does not affect samples.