Discuss the relative reliability of the different types of audit procedures

Inspection of tangible assets, reperformance, and recalculation are generally considered of high reliability because the auditor has direct knowledge about them. Inspection of records and documents, confirmation, analytical procedures, and scanning are generally considered to be of medium reliability. The reliability of inspection of records and documents depends primarily on whether a document is internal or external. Scanning depends on the auditor's ability to identify anomalous items using judgment or CAATs. The form of the confirmation, prior experience with the entity, the nature of the information being confirmed, and the intended respondent affect the reliability of confirmations. The reliability of analytical procedures may be affected by the quality of the client's internal control system. Finally, inquiry and observation are generally low-reliability types of evidence since both require further corroboration by the auditor. 
 It should be understood, however, that levels of reliability for the types of evidence should be considered as general guidelines. The reliability of the types of evidence may vary considerably across entities, and it is subject to a number of exceptions.