Regression testing is a way to confirm that features working prior to any change are still working. Regression testing should involve either the most commonly used functions in the system and/or the most high-risk functions determined during risk-analysis to determine whether or not a particular software update has changed something not directly addressed in the vendor’s documentation. That is to confirm that the system itself has not regressed or that a change has not introduced some kind of an unintended failure.record but also the changes or the deletion of records. If the system has limited or incomplete audit trail ability, then the record must be supplemented in some other way, often taking the form of paper records. For example, a use notebook next to an instrument. Technical controls make everybody’s life much simpler.