Attribute sampling method (either control is present or absent) will be useful when testing for compliance. Either access given as per authorization matrix or not given as per authorization matrix. Discovery sampling is used when an auditor is trying to determine whether a type of event has occurred, and therefore it is suited to assess the risk of fraud and to identify whether a single occurrence has taken place. Stop-or-go-sampling is used when auditor believes that very few errors will be found. It prevents excessive sampling by allowing an audit test to be stopped at the earliest possible moment. Stratified mean per unit and unstratified mean per unit are used in variable sampling.