... of data. The data held on a computer may become incorrect, corrupt or of 'poor quality'. This could happen at different stages of data processing. 1. Errors in the Input. Data may be keyed in wrongly. 2. Errors in Operating Procedure. An update program may be ran twice in error, thus the master file would be updated twice. 3. Program errors could lead to corruption of files. A new system may have errors in it which may not surface for some time, but they may be introduced during program maintenance. Standard Clerical procedures To protect against input and operating, procedures can be documented and followed for both input and output. Input * Data entry must be limited to authorized personnel only * In large volume data entry, data may be verified (keyed in twice), to guard against keying errors * Data control totals must be used wherever possible to verify the completeness and accuracy of the data, and to ...

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