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This reminds me of an excellent talk my friend Dan Slimmon gave called "Car Alarms and Smoke Alarms". He relates monitoring to the concepts of sensitivity and s

by beat 12y ago

This reminds me of an excellent talk my friend Dan Slimmon gave called "Car Alarms and Smoke Alarms". He relates monitoring to the concepts of sensitivity and specificity in medical testing (http://en.wikipedia.org/wiki/Sensitivity_and_specificity http://en.wikipedia.org/wiki/Sensitivity_and_specificity). Sensitivity is about the likelihood that your monitor will detect the error condition. Specificity is about the likelihood that it will not create false alarms. Think about how people react to smoke alarms versus car alarms. When the smoke alarm goes off, people mostly follow the official procedure. When car alarms go off, people ignore them. Why? Car alarms have very poor specificity. I'd add another layer of car alarms are Not My Problem, but that's just me and not part of Dan's excellent original talk.

larrys 12y ago
Would add another dimension to car vs. smoke alarms. [1] Smoke alarms are loud and typically near you (think about the one that goes off in the kitchen because of burning pizza in the oven). So you have to react or you are paralyzed. You fan it almost immediately. You have to. Car alarm typically you can't do anything (unless it's your car) and the noise, while annoying, is not as close or as loud as a smoke alarm. [1] Edit: Distance from and the decibels of the alarm and what you can do about the alarm. Of course there are also building alarms (follow procedure) and alarms in your own house "get the noise to stop!"
- x1798DE 12y ago
  Yeah, I think this actually may explain things better than specificity. Even if the false alarm rate is low, the rate of actual, life-threatening fires is incredibly low in modern day, so chances are almost every time you hear a fire alarm go off it's alerting you essentially erroneously. I get the impression that in a home the "standard procedure" for dealing with fire alarms is to open windows, fan the smoke away from the thing and/or take the batteries out of the alarm.
  - dllthomas 12y ago
    It depends. The rate of smoke alarms going off inadvertently while someone is cooking is high compared to the actual incidence of fires. The rate of smoke alarms going of when no one is doing anything heat-related is clearly lower. If you are a person who just burned some toast, that is almost certainly the reason the smoke alarm is going off, and it's entirely reasonable to address the symptoms. If you are a person who woke up to a smoke alarm, and no one else was cooking anything, things are a little different.
    - x1798DE 12y ago
      I don't know if I've ever experienced personal (home) fire alarms going off for no reason, and I've never had them go off because of an actual fire, but I have had them go off when someone else is cooking (alerting me that someone is cooking, whether or not I knew that), or due to steam from a shower, if they are placed wrong - again, whether or not I knew someone was taking a shower. In corporate/organizational environments - often in buildings made entirely of concrete - I've had them go off very frequently, but almost never as a result of a dangerous condition - usually either a drill, a small fire that was immediately put out, someone pulling the fire alarm as a prank/protest or something else like someone burning popcorn or something. I still think the point stands.
      - dllthomas 12y ago
        Which point? My point was that in a (nonadversarial) context where you have known triggers for false alarms, P(problem|alarm) falls dramatically once you have identified the presence of such a trigger, and it's entirely reasonable for our actions to reflect this.
- bokchoi 12y ago
  So all we need to do is have car alarms be sent directly to you (to your phone or your house) and be loud.
  - r00fus 12y ago
    That'd be nice. Make it a loud part of the key fob? Maybe then the owner would be less inclined to accept a car alarm with a hair-trigger.
    - dllthomas 12y ago
      And more likely to notice, and more able to find his keys... seems like a win all 'round.
      - yuliyp 12y ago
        And if someone parks like an asshole, you trigger their car alarm and embarrass him in front of everyone they're around. bonus win.
  - jschwartzi 12y ago
    Just put a cell radio in it. As a bonus it can transmit GPS coordinates to you so you can watch it get stolen in real time.
learningram 12y ago
Link I found of the lecture http://vimeo.com/95073903 http://vimeo.com/95073903
Moru 12y ago
We just got new fire alarms installed in our building. They go off 2-4 times per day and everyone just ignores them. It's enough to toast your bread lightly brown to go off. You can easily hear the neighbours fire alarms. There is no way of removing the battery in the new alarms, the only thing you can do is take it down and stuff it in a drawer somewhere. Not even pushing the button helps. This makes them totally useless, even more so than a car alarm. We got ours exchanged and they go off much less now luckily.
- praneshp 12y ago
  If you're in the US, watch out. I think there are laws against tampering with fire alarms. (Though I think you're in a ridiculous situation)
- scoot 12y ago
  > Not even pushing the button helps. If it's like every other smoke detector I've encountered, the bottom is to test the alarm, not to cancel it.
  - kevinbowman 12y ago
    I've got a mains-attached one (ie not solely battery powered), and the button is "hush" which silences it for 5 mins (although it chirps once per minute to remind you that it's hushed). If you hold the button whilst it's not going off, it tests the alarm.
  - cdr 12y ago
    All the storebought smoke alarms I've seen in the past few years have two buttons (or one button with two functions) - one to test, one to shut it off for a few minutes when something besides a housefire is making it go off. It may vary by country I suppose.
- sysworld 12y ago
  Your lucky, when someone in my building triggers the fire alarm for there flat, the really loud alarm sounds in all the flats in the building, with an audio note saying that someone has triggered the fire alarm and you can leave if you want, but it's not required. I guess it will tell you when they have confirmed it's a real fire, and you really have to leave.
bane 12y ago
A similar lesson most of us are probably familiar with. http://en.m.wikipedia.org/wiki/Boy_who_cried_wolf http://en.m.wikipedia.org/wiki/Boy_who_cried_wolf
bane 12y ago
A similar lesson most of us are probably familiar with. http://en.m.wikipedia.org/wiki/Boy_who_cried_wolf http://en.m.wikipedia.org/wiki/Boy_who_cried_wolf
rhizome 12y ago
Another thing about car alarms: how many people even know what their own car alarm sounds like?
- nucleardog 12y ago
  Unless you have some fancy/aftermarket thing, it sounds just like your horn which you probably hear every time you use the key fob to lock it. Whether you have the ability to differentiate your particular tone of horn from all the others is a whole different story.
luch 12y ago
On the same topic, I've heard that every supertanker has a proximity radar in order to avoid to collide with small boats. However, in some heavy-traffic routes like the Straight of Dover or Gibraltar the proximity alarm goes off constantly. So the commanding officers usually disable them, leading to a good number of accidents with fishermen boats.

by beat 12y ago

larrys 12y ago

Would add another dimension to car vs. smoke alarms. [1] Smoke alarms are loud and typically near you (think about the one that goes off in the kitchen because of burning pizza in the oven). So you have to react or you are paralyzed. You fan it almost immediately. You have to. Car alarm typically you can't do anything (unless it's your car) and the noise, while annoying, is not as close or as loud as a smoke alarm. [1] Edit: Distance from and the decibels of the alarm and what you can do about the alarm. Of course there are also building alarms (follow procedure) and alarms in your own house "get the noise to stop!"

x1798DE 12y ago
Yeah, I think this actually may explain things better than specificity. Even if the false alarm rate is low, the rate of actual, life-threatening fires is incredibly low in modern day, so chances are almost every time you hear a fire alarm go off it's alerting you essentially erroneously. I get the impression that in a home the "standard procedure" for dealing with fire alarms is to open windows, fan the smoke away from the thing and/or take the batteries out of the alarm.
- dllthomas 12y ago
  It depends. The rate of smoke alarms going off inadvertently while someone is cooking is high compared to the actual incidence of fires. The rate of smoke alarms going of when no one is doing anything heat-related is clearly lower. If you are a person who just burned some toast, that is almost certainly the reason the smoke alarm is going off, and it's entirely reasonable to address the symptoms. If you are a person who woke up to a smoke alarm, and no one else was cooking anything, things are a little different.
  - x1798DE 12y ago
    I don't know if I've ever experienced personal (home) fire alarms going off for no reason, and I've never had them go off because of an actual fire, but I have had them go off when someone else is cooking (alerting me that someone is cooking, whether or not I knew that), or due to steam from a shower, if they are placed wrong - again, whether or not I knew someone was taking a shower. In corporate/organizational environments - often in buildings made entirely of concrete - I've had them go off very frequently, but almost never as a result of a dangerous condition - usually either a drill, a small fire that was immediately put out, someone pulling the fire alarm as a prank/protest or something else like someone burning popcorn or something. I still think the point stands.
    - dllthomas 12y ago
      Which point? My point was that in a (nonadversarial) context where you have known triggers for false alarms, P(problem|alarm) falls dramatically once you have identified the presence of such a trigger, and it's entirely reasonable for our actions to reflect this.
bokchoi 12y ago
So all we need to do is have car alarms be sent directly to you (to your phone or your house) and be loud.
- r00fus 12y ago
  That'd be nice. Make it a loud part of the key fob? Maybe then the owner would be less inclined to accept a car alarm with a hair-trigger.
  - dllthomas 12y ago
    And more likely to notice, and more able to find his keys... seems like a win all 'round.
    - yuliyp 12y ago
      And if someone parks like an asshole, you trigger their car alarm and embarrass him in front of everyone they're around. bonus win.
- jschwartzi 12y ago
  Just put a cell radio in it. As a bonus it can transmit GPS coordinates to you so you can watch it get stolen in real time.

learningram 12y ago

Link I found of the lecture http://vimeo.com/95073903 http://vimeo.com/95073903

Moru 12y ago

We just got new fire alarms installed in our building. They go off 2-4 times per day and everyone just ignores them. It's enough to toast your bread lightly brown to go off. You can easily hear the neighbours fire alarms. There is no way of removing the battery in the new alarms, the only thing you can do is take it down and stuff it in a drawer somewhere. Not even pushing the button helps. This makes them totally useless, even more so than a car alarm. We got ours exchanged and they go off much less now luckily.

praneshp 12y ago
If you're in the US, watch out. I think there are laws against tampering with fire alarms. (Though I think you're in a ridiculous situation)
scoot 12y ago
> Not even pushing the button helps. If it's like every other smoke detector I've encountered, the bottom is to test the alarm, not to cancel it.
- kevinbowman 12y ago
  I've got a mains-attached one (ie not solely battery powered), and the button is "hush" which silences it for 5 mins (although it chirps once per minute to remind you that it's hushed). If you hold the button whilst it's not going off, it tests the alarm.
- cdr 12y ago
  All the storebought smoke alarms I've seen in the past few years have two buttons (or one button with two functions) - one to test, one to shut it off for a few minutes when something besides a housefire is making it go off. It may vary by country I suppose.
sysworld 12y ago
Your lucky, when someone in my building triggers the fire alarm for there flat, the really loud alarm sounds in all the flats in the building, with an audio note saying that someone has triggered the fire alarm and you can leave if you want, but it's not required. I guess it will tell you when they have confirmed it's a real fire, and you really have to leave.

bane 12y ago

A similar lesson most of us are probably familiar with. http://en.m.wikipedia.org/wiki/Boy_who_cried_wolf http://en.m.wikipedia.org/wiki/Boy_who_cried_wolf

bane 12y ago

A similar lesson most of us are probably familiar with. http://en.m.wikipedia.org/wiki/Boy_who_cried_wolf http://en.m.wikipedia.org/wiki/Boy_who_cried_wolf

rhizome 12y ago

Another thing about car alarms: how many people even know what their own car alarm sounds like?

nucleardog 12y ago
Unless you have some fancy/aftermarket thing, it sounds just like your horn which you probably hear every time you use the key fob to lock it. Whether you have the ability to differentiate your particular tone of horn from all the others is a whole different story.

luch 12y ago

On the same topic, I've heard that every supertanker has a proximity radar in order to avoid to collide with small boats. However, in some heavy-traffic routes like the Straight of Dover or Gibraltar the proximity alarm goes off constantly. So the commanding officers usually disable them, leading to a good number of accidents with fishermen boats.