What are the best auditing methods using CAAT?

The use of Computers as a tool to perform audit procedure are often refered as "CAAT".

1- Audit Software

2- Test Data

In my opnion I believe Audit Software is the best method coz it will scrutinise large volume of data which is almost impossbile if the auditor will examine it manually.

Whereas, In case of Test Data Auditors are inserting Dummy data in the client system which contain errors in order to verify that the Clients system is operating effectively and it prevent / detect or correct the misstatement. Usually clients does not appreciate the use of test data method.