Reasons for controlling data inputs:
o To check and ensure the accuracy of the data inputs.
o To check and ensure the completeness of data which has been input.
o To ensure that the output information is free from error thus enabling it to be used to generate desired results.
Methods that may be used to control data inputs:
1. Control totals
These are totals established beforehand for input and processing transactions. These totals can range from a simple document count to totals for quantity fields such as total sales amount (for a batch of transactions). Computer programs count the totals from transactions input or processed.
2. Edit checks
These are programmed routines that can be performed to edit input data for errors before they are processed. Transactions that do not meet edit criteria will be rejected. For example, data might be checked to make sure they were in the right format (a 9-digit social security number should not contain alphabetic characters). Edit checks may include sequence checks, limit checks, range checks, etc
3. Computer matching
This matches input data with information held on master or suspense files, with unmatched items noted for investigation. For example, a matching program might match employee time cards with a payroll master file and report missing or duplicate time cards
4. Check digit
A numeric value that has been calculated mathematically is added to data to ensure that the original data have not been altered or an incorrect value submitted. This control is effective in detecting transposition and transcription errors. For example, a check digit is added to an account number so that it can be checked for accuracy when it‘s used.
5. Reasonableness check.
6. Completeness check.