Sure: It's easy to have no false alarms; just turn off the detector! It's easy to have no missed detections of real problems; just sound the alarm all the tim

Sure: It's easy to have no false alarms; just turn off the detector! It's easy to have no missed detections of real problems; just sound the alarm all the time. Then it's easy to have whatever false alarm rate want; just 'interpolate' between these two detectors. Such detectors are known as 'trivial' with good justification. If some monitoring software claims a low false alarm rate, then, sure, that's easy to get -- just use a trivial detector! And for being useful, if have two detectors that actually are good and want to 'interpolate' between them, then a trivial detector can do that and be 'useful'.