Audit Sampling

ISA 530 Audit Sampling and Other Selective Testing Procedures states Audit sampling is the application of a compliance or substantive procedure to less than 100% of the items within an account balance or class of transactions such that all sampling units have a chance of selection. To enable the auditor to obtain and evaluate evidence of some characteristics of the balance or class and to form or assist in forming a conclusion concerning the population from which the sample is drawn.  

There are two manners to sampling in auditing:

i. Judgement sampling (or non statistical)
ii. Statistical sampling