Makes me think of those STUPID Brinks Security commercials where the guy breaking in runs away after he hears the "alarm" and the person (usually a woman) gets a phone call asking if shes ok.
Sure an alarm may make normal, rational burglars run off, but ifs its a drug crazed psychopath whos purpose is to get YOU and not your TV, your in a world of hurt if you think the "alarm" is going to scare him off.