5 ms·

> Of those people that die, over 80% of them are not wearing a life jacket or Personal Flotation Device (PFD). Making this statement in such a context borders

by robryk 4y ago

> Of those people that die, over 80% of them are not wearing a life jacket or Personal Flotation Device (PFD). Making this statement in such a context borders on statistical misconduct, because it ignores base rates: Consider whether you'd find a statement that ">90% of injured car passengers were not wearing helmets" as a valid argument for helmet-wearing. This is presented as an argument for PFD-wearing.

jefftk 4y ago
Car passengers rarely wear helmets, but don't most paddlers wear life jackets? When I see people out on the river they're almost always wearing them.
- robryk 4y ago
  This is exactly my point. Without knowing how common {wearing helmets in cars, wearing PFDs in kayaks} is, the statements imply nothing about safety benefits of either, and yet that one was presented in a way that suggests that it does. What would be a non-misleading value to quote would be absolute change of risk of drowning (e.g. that a typical trip without a PFD costs X micromorts, while a typical trip with one Y micromorts). What would be less problematic (but still potentially misleading[1]) would be a relative risk reduction (wearing PFD makes you X times less likely to die). [1] Because it doesn't tell you anything about the original risk that you're lowering. E.g. helmets are a good protection against falling bricks: equally good at construction sites as when you're walking down the street. The only difference is that falling bricks are more likely on a construction site.
  - bananasbandanas 4y ago
    While it's shoddy statistics, at least in this case the implied effect seems to be real. According to these two sources [1][2] that just came up when I searched for this, prevalence of wearing life-jackets among kayakers appears to be ~78%. [1] https://injuryprevention.bmj.com/content/4/3/203 https://injuryprevention.bmj.com/content/4/3/203 [2] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5931488/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5931488/
    - robryk 4y ago
      I have very little doubt the effect's real. Note though that getting base rates from one place and getting rates of accidents from another is usually a bad idea: they will have various ways of measuring the rates, so will have different biases (based on location, time-of-day, time-of-year, ... where the measurement happens).
- pvaldes 4y ago
  > don't most paddlers wear life jackets? It depends on the area, difficulty level and water temperature. Life jackets have pros and cons. Can be an obstacle when swimming after a drifting kayak or even worse rescuing somebody that fell in the water. A jacket will also block you to get impulse to return to the kayak in some cases (because you are unable to submerge). I often don't wear one but the children must wear it. Of course in the sea the idea of not wearing a jacket is out of the discussion
CapmCrackaWaka 4y ago
Technically your point is true, but I find these types of gotchas in bad faith. A more fair comparison to this statement would be ">90% of injured car passengers were not wearing seat belts". The author was trying to stress the importance of wearing a life jacket, I don't think they need to get into statistical robustness in their summary paragraph for something that is so _obviously_ correct. The only reason you would want to argue this point is if you think they are being intentionally misleading, which I highly doubt you do.
- robryk 4y ago
  > The author was trying to stress the importance of wearing a life jacket, I don't think they need to get into statistical robustness in their summary paragraph for something that is so _obviously_ correct. Then don't provide statistics and just state that it's obviously correct. If doing so is less convincing, then it means that the statement _was_ misleading. > The only reason you would want to argue this point is if you think they are being intentionally misleading, which I highly doubt you do. I think they believe the conclusion is true and are intentionally saying whatever they can to make people think it's true, regardless of whether the reasoning they imply is correct. E: So, in my estimation they are intentionally misleading in the area of valid arguments and not in the area of water safety.
snowwrestler 4y ago
Passengers would in fact have a lower chance of injury in a car crash if they were wearing helmets. So why don’t they? Because helmets are expensive, uncomfortable, and—worst of all—totally uncool. One reason this video is focused on advertising is because that helps set the baseline for social acceptance of things like PFDs and sober paddling. If every single person I see in a kayak ad is wearing a PFD, it will seem less weird to wear a PFD when I go kayaking.
- djbusby 4y ago
  Helmets are cool.
- kazinator 4y ago
  I would not be able to sit in most compact and subcompact cars if I were wearing a helmet, due to inadequate headroom clearance.
- robryk 4y ago
  > Passengers would in fact have a lower chance of injury in a car crash if they were wearing helmets. I once thought so. Someone pointed out that helmets might make whiplash worse (because they extend the head backward, so will change the angle at which the head impacts the headrest) and that we're essentially using airbags for (a.o.) the same functionality (protection from direct strikes to the head). So, I'm ambivalent on the topic now.
  - scarier 4y ago
    Check out frontal head restraint systems. In combination with a good harness they eliminate the C-spine concern, at the cost of reducing your field of regard a bit. If they can figure out the mobility piece, I’d happily drive with one on the street over air bags.
  - nkurz 4y ago
    Are you familiar with the "Davies Craig Motoring Helmet"? It's a real Australian product from the 80's. They did considerable research and claimed considerable safety benefit. I'm not sure how it interacts with airbags, but here's a link: https://www.whichcar.com.au/car-style/davies-craig-australian-car-helmet https://www.whichcar.com.au/car-style/davies-craig-australia....
Dannymetconan 4y ago
Its is about as misleading as saying "X% of them are not wearing a seatbelt" the helmet comparison is not fair here. In every US state (as far as I can tell) you are required to wear a seatbelt while operating a car. Similarly in nearly every US state you are also required to wear a PFD while operating a personal watercraft. Enforcement seems a lot more lax on this though. The legal status of the requirement makes this a valid comparison though it is implicit. This isn't an extra safety device. Though like helmets on motorbikes it is still one an individual may choose to forgo. https://www.boatsafe.com/pfd-requirements-state-boating-regulations/ https://www.boatsafe.com/pfd-requirements-state-boating-regu...

by robryk 4y ago

jefftk 4y ago

Car passengers rarely wear helmets, but don't most paddlers wear life jackets? When I see people out on the river they're almost always wearing them.

robryk 4y ago
This is exactly my point. Without knowing how common {wearing helmets in cars, wearing PFDs in kayaks} is, the statements imply nothing about safety benefits of either, and yet that one was presented in a way that suggests that it does. What would be a non-misleading value to quote would be absolute change of risk of drowning (e.g. that a typical trip without a PFD costs X micromorts, while a typical trip with one Y micromorts). What would be less problematic (but still potentially misleading[1]) would be a relative risk reduction (wearing PFD makes you X times less likely to die). [1] Because it doesn't tell you anything about the original risk that you're lowering. E.g. helmets are a good protection against falling bricks: equally good at construction sites as when you're walking down the street. The only difference is that falling bricks are more likely on a construction site.
- bananasbandanas 4y ago
  While it's shoddy statistics, at least in this case the implied effect seems to be real. According to these two sources [1][2] that just came up when I searched for this, prevalence of wearing life-jackets among kayakers appears to be ~78%. [1] https://injuryprevention.bmj.com/content/4/3/203 https://injuryprevention.bmj.com/content/4/3/203 [2] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5931488/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5931488/
  - robryk 4y ago
    I have very little doubt the effect's real. Note though that getting base rates from one place and getting rates of accidents from another is usually a bad idea: they will have various ways of measuring the rates, so will have different biases (based on location, time-of-day, time-of-year, ... where the measurement happens).
pvaldes 4y ago
> don't most paddlers wear life jackets? It depends on the area, difficulty level and water temperature. Life jackets have pros and cons. Can be an obstacle when swimming after a drifting kayak or even worse rescuing somebody that fell in the water. A jacket will also block you to get impulse to return to the kayak in some cases (because you are unable to submerge). I often don't wear one but the children must wear it. Of course in the sea the idea of not wearing a jacket is out of the discussion

CapmCrackaWaka 4y ago

Technically your point is true, but I find these types of gotchas in bad faith. A more fair comparison to this statement would be ">90% of injured car passengers were not wearing seat belts". The author was trying to stress the importance of wearing a life jacket, I don't think they need to get into statistical robustness in their summary paragraph for something that is so _obviously_ correct. The only reason you would want to argue this point is if you think they are being intentionally misleading, which I highly doubt you do.

robryk 4y ago
> The author was trying to stress the importance of wearing a life jacket, I don't think they need to get into statistical robustness in their summary paragraph for something that is so _obviously_ correct. Then don't provide statistics and just state that it's obviously correct. If doing so is less convincing, then it means that the statement _was_ misleading. > The only reason you would want to argue this point is if you think they are being intentionally misleading, which I highly doubt you do. I think they believe the conclusion is true and are intentionally saying whatever they can to make people think it's true, regardless of whether the reasoning they imply is correct. E: So, in my estimation they are intentionally misleading in the area of valid arguments and not in the area of water safety.

snowwrestler 4y ago

Passengers would in fact have a lower chance of injury in a car crash if they were wearing helmets. So why don’t they? Because helmets are expensive, uncomfortable, and—worst of all—totally uncool. One reason this video is focused on advertising is because that helps set the baseline for social acceptance of things like PFDs and sober paddling. If every single person I see in a kayak ad is wearing a PFD, it will seem less weird to wear a PFD when I go kayaking.

djbusby 4y ago
Helmets are cool.
kazinator 4y ago
I would not be able to sit in most compact and subcompact cars if I were wearing a helmet, due to inadequate headroom clearance.
robryk 4y ago
> Passengers would in fact have a lower chance of injury in a car crash if they were wearing helmets. I once thought so. Someone pointed out that helmets might make whiplash worse (because they extend the head backward, so will change the angle at which the head impacts the headrest) and that we're essentially using airbags for (a.o.) the same functionality (protection from direct strikes to the head). So, I'm ambivalent on the topic now.
- scarier 4y ago
  Check out frontal head restraint systems. In combination with a good harness they eliminate the C-spine concern, at the cost of reducing your field of regard a bit. If they can figure out the mobility piece, I’d happily drive with one on the street over air bags.
- nkurz 4y ago
  Are you familiar with the "Davies Craig Motoring Helmet"? It's a real Australian product from the 80's. They did considerable research and claimed considerable safety benefit. I'm not sure how it interacts with airbags, but here's a link: https://www.whichcar.com.au/car-style/davies-craig-australian-car-helmet https://www.whichcar.com.au/car-style/davies-craig-australia....

Dannymetconan 4y ago

Its is about as misleading as saying "X% of them are not wearing a seatbelt" the helmet comparison is not fair here. In every US state (as far as I can tell) you are required to wear a seatbelt while operating a car. Similarly in nearly every US state you are also required to wear a PFD while operating a personal watercraft. Enforcement seems a lot more lax on this though. The legal status of the requirement makes this a valid comparison though it is implicit. This isn't an extra safety device. Though like helmets on motorbikes it is still one an individual may choose to forgo. https://www.boatsafe.com/pfd-requirements-state-boating-regulations/ https://www.boatsafe.com/pfd-requirements-state-boating-regu...