Data validation means ensuring the internal integrity of the data. For example, the date of operation can be not earlier than the date of birth. The validation rules are the derived from the logical construction of the modeled reality.
The data validation Procedure was designed to improve the quality of data by finding inconsistencies in the data. For example, the patient's birth date can't be later than the date of the operation. There is a number of validation rules that the record has to meet in order to be published. Some of the data may be labeled "incorrect" by the computer by may in fact be correct which the owners of the data can confirm, for example unusual age and weight combinations. In such case, the hospital can mark the record as correct, despite not meeting the validation rule (see validation rules). The last word belongs to the data manager. He is the one to finally accept or reject the record.
Please note, that validated data can be still not true, it can still not reflect the facts. To be sure that the data represents the truth (the facts), the data verification must be performed.