Each metric evaluates a different factor in security program effectiveness. Metrics can be used in combination to achieve a complete picture of overall system effectiveness. Some metrics are useful for both new and existing security facilities, and others are only applicable to existing facilities. The key to dealing with intrusion threat actors is to detect them with a superior response before they can make their way to their intended target. Each attacker must make entry, make his or her way through various gates, doors, corridors and then finally to the target.”]