Validation and Verification : Dual Input

The dual input method of verification is used when data is entered at the keyboard. The data to be entered is typed in twice by two different operators. The two copies of the data are then compared. Any differences are detected. The operators will be prompted to retype the sections that differ until both copies agree. When the two copies agree it is assumed by the computer that the data has been entered correctly.

This method of verification is very reliable. It is highly unlikely that any data can be incorrectly transferred into a computer system when the dual input system is used. Unfortunately it is very expensive to use. If data has to be entered twice then it will take twice as long to enter the data or twice as many people will have to be employed.

GCSE ICT Companion 04 - (C) P Meakin 2004