Audit sampling involves applying audit procedures to less than 100% of items in an account balance or class of transactions. There are various statistical and nonstatistical sampling methods that can be used including attributes sampling, variables sampling, and probability-proportional-to-size sampling. The key steps in any audit sampling application are to determine the sampling objective, define the population and sampling unit, determine the appropriate sample size, select the sample, test the sample items, evaluate the sample results against established criteria, and document the sampling procedure.