In addition to direct testing of program logic, the auditor can achieve some degree of
assurance by reviewing error listings and error logs. These documents provide evidence
of the effectiveness of the data entry process, the types and volume of errors encountered,
and the manner in which the errors are corrected and reentered into the system. Error
listings and logs do not, however, provide evidence of undetected errors. An analysis of
error conditions not present in the listing can be used to guide the auditor in designing
substantive tests to perform. For example, assume that the error listing of the sales invoice
file contains no price limit errors. On the one hand, this situation might simply mean that
sales personnel strictly adhere to pricing guidelines. On the other hand, it may mean that the
validation program does not test for this type of error. To determine whether material
price discrepancies exist in the sales invoice file, the auditor can perform substantive
tests that compare the actual price charged with the suggested retail price.