Data Validation Controls
Input validation controls are intended to detect transcription errors in transaction data
before they are processed. Since errors detected early are less likely to infiltrate the
accounting records, validation procedures are most effective when they are performed
as close to the source of the transaction as possible. In the batch system depicted in
Figure 9.1, data validation occurs only after the goods have been shipped. Extensive error
logs, error correction, and transaction resubmission procedures characterize such systems.
By contrast, validity tests performed in real time and POS systems can deal with
most errors as they occur. This approach also minimizes human data entry and thus reduces
the risk of data entry errors. For example, when the clerk enters the customer’s
account number, the system automatically retrieves his or her name and mailing address.
When the clerk enters the product number and quantity sold, the data entry system
automatically retrieves the product description and price, and then calculates the extended
price plus tax and shipping charges.