The rapid increase in the size of U.S. companies from the early twentieth century created the need for audit procedures based on the selection of a part of the total population audited to obtain reliable audit evidence, to characterize the entire population consists of account balances or classes of transactions. Sampling is not used only in audit – is used in sampling surveys, market analysis and medical research in which someone wants to reach a conclusion about a large number of data by examining only a part of these data. The difference is the “population” from which the sample is selected, ie that set of data which is intended to draw a conclusion. Audit sampling applies only to certain types of audit procedures.