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Ann R. Thryft
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Re: False positives versus false negatives
Ann R. Thryft   2/3/2012 12:11:07 PM
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No matter where I've lived--in the middle of Los Angeles or a nice suburban town in Northern California--no one pays any attention to car alarms. I would think that's even truer, if that's possible, in NY. I agree about the possible law, and have been amazed such a one has never passed, even here in litigious California.

Alexander Wolfe
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Re: False positives versus false negatives
Alexander Wolfe   2/2/2012 4:34:14 PM
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Your example of a car alarm is a good one, in that the false alarm rate is so high that these alarms are essentially ignored. Indeed, there can and should be a law that that audible alarm portion of car alarms have to be disabled. The siren serves no purpose. The function of a car alarm is to disable the capability of starting the car. That's how it prevents theft, not by warbling so that some samaritan will come by and smite the potential car thief. I live in NY, and if your car alarm goes off, your automobile is on its own, buddy. Nobody's gonna come by and tell anyone to step away from the vehicle..

Ann R. Thryft
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Re: False positives versus false negatives
Ann R. Thryft   2/2/2012 2:48:36 PM
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I haven't been in hotels with false alarms in the middle of the night--that must be terrifying!--but I sure do remember the MGM Grand fire. It's made me nervous about staying in multi-story hotels ever since. I agree, a high rate of false alarms makes us tend to ignore them. Just think about car alarms! The universal signal to ignore an alarm, and a good example of the cry wolf phenomenon (for those who grew up reading fairy tales).


Tim
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Re: One siren you don't want to hear
Tim   1/28/2012 5:18:33 PM
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In my grade school, we had fire drills religiously where we marched outside and lined up in our appropriate class lines and waited for the all clear from our school safety officer.  That was until we had an actual fire in the school.  At this point, the alarm did not go off.  Instead the principal called all people on the PA system and told everyone stay in their class rooms until the smoke had cleared.  I to this day do not know the rationale of this decision, nor do I know why we did not follow the drill.  I guess some plans are only plans until there is an actual problem.

Charles Murray
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Re: False Alarms
Charles Murray   1/26/2012 10:25:22 PM
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I agree, Tool_maker. I am always amazed at the patience and dogged pursuit of the problems by so many of the contributors in the Sherlock Ohms story. This is a classic example, performed in a very important setting.

Alexander Wolfe
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Re: False positives versus false negatives
Alexander Wolfe   1/26/2012 6:27:20 PM
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This may seem like an insignificant and tangential comment, but apropos of false alarms I just realized that I've been in many hotel situations in the past several years where an earsplitting alarm went off in the middle of the night, you get up worried and don't know what to do, often opening the door a bit in your underwear to find out what's up, and then the alarm shuts off and end of story. No fire, no explanation. This is dangerous because it trains you to ignore hotel fire alarms, so when the real one comes one day, you're gonna be in trouble. This is not trivial. Remember the MGM Grand fire in Las Vegas in 1980? False alarms are a dangerous design flaw. More properly, there will always be false alarms (if you stanch them completely you will miss some real situations). The problem is when you have too high a false alarm rate.

Ralphy Boy
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Re: False Alarms
Ralphy Boy   1/26/2012 4:15:29 PM
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Hey Rob...

Thanks for the invite. I'm honored... I want to run it by the boss first though.

Ralph

Rob Spiegel
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Re: False Alarms
Rob Spiegel   1/26/2012 11:53:09 AM
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RalphyBoy, this would make a good Sherlok Ohms posting. It's just the kind of story we're always looking for.

It would need a tad more detail, but not much. If you're interested, please let me know at: rob.spiegel@ubm.com

We would also need a short bio -- two to four sentences.

Tool_maker
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Re: False Alarms
Tool_maker   1/26/2012 10:03:34 AM
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@Ralphy Boy: Your last sentence is true in every line of work. Whether it is a safety system in a power plant, the ignition system in your car or an irregular heartbeat, being able to replicate the problem so one knows what to repair is a gift from God. Either that or dumb luck.

My hat is off to the man who solved this problem.

Charles Murray
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Re: False positives versus false negatives
Charles Murray   1/25/2012 7:34:11 PM
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I periodically visited nuclear plants as part of my job in the late '70s and never heard, nor heard of, a siren going off outside. I agree with you, Alex, this is not a small issue. It's scary to think that the problem became evident in retrospect, rather than being prevented in the first place.

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