Whenever data is copied manually, there is a chance that mistakes will be made. This can be for a number of reasons:
The person doing the copying may misread the original data
Long codes which have no (human) meaning are especially prone to input error
A common typing error is a transposition errorTyping error, where two characters are swapped – where two characters are accidentally swapped, e.g. age 18 incorrectly entered as 81
An omission errorTyping error where data is lost or omitted from entry is when data is omitted or excluded. Data could be lost, damaged or overlooked prior to entry into the computerised system
validationChecking input data is sensible and in the right format. is an automatic computer check to ensure that the data entered is sensible and reasonable. It does not check the accuracy of data.
Examples of validation checks:
Presence check: Ensures that data has been entered into a data field, i.e. it is not blank
Length check: Ensures that data entered has the correct number of characters, or isn't longer than a certain number of characters. For example, a full UK mobile telephone number is typically 11 digits long
Type check: Ensures that data entered is of the correct data type, e.g. text/numbers
Format check: Ensures that data entered is in a specific format, e.g. dates written as dd/mm/yyyy
Range check: Ensures that data entered is within a given range, e.g. a value between 1 and 100