We are all unique - like snowflakes

There has been a flurry of news from the Braidwood Inquiry in Vancouver over the past day or two about various experts proposing how the safety issue with tasers may be related to heart disease.

For example: Pierre Savard, of Montreal's Ecole Polytechnique, a biomechanical engineer says heart disease increases the probability of death after a taser shock. ... He said his conclusion is in accordance with the product warnings issued by Taser International. Company literature says there is a risk of injury or death due to individual susceptibilities. [LINK]

[First of all, his statement about the product warnings from Taser make me suspect that he may be assisting, intentionally or not, Taser with their Great Escape from Liability. I'm trying to imagine why he would have added that point... As I've already posted, the heart of the liability issue may rest with the training.] [LINK]

Let's examine this blame-shifting argument that some individual susceptibilities are the real issue. Their argument has a subtle but significant flaw, as you will soon see.

First - it appears that everyone is now in agreement that the overall death rate 'for individuals subdued by police using a taser' is 1.4% (or 1-in-70). But when we renormalize this number to estimate the death rate for just the most dangerous full-on X26 tasers across the chest (as opposed to all taser deployments), it becomes something several times larger (getting into the ~5% range). [LINK]

So, what percentage of individuals walking the streets have this alleged individual coronary susceptibility?

It can't be too high a proportion (like 50%), because it would simply become a normal human condition. 20% is probably a non-starter by the same logic. Even 10% would be a stretch for something that is supposed to be individual, unique and not too common.

On the other hand, if this alleged coronary susceptibility condition is assumed to be 5% (for a well-chosen example), then it would mean that the full-on x26 taser across the chest death rate for this group becomes 100% (to match the agreed death rate renormalized for the worst case deployment). So it can only be as low as 5% if they allow that the associated death rate is 100%.

One of my unspoken assumptions [for this rebuttal] is actually their assumption: the taser victims that are most likely to die are those that are most susceptible.

If we ask Taser (or these semi-supportive experts) what they estimate to be the proportion of the population that have these alleged individual susceptibilities, then the answer must be bound to fairly tight limits by common sense on the high side, and by the actual (estimated) death rate (renormalized) on the low side. In fact, there's hardly any room at all in between those limits.

An informed exchange would unfold thus:

Q: "What proportion of the population have these so-called individual susceptibilities?"
A: "Oh - maybe 10 to 20%"
Q: "That seems a bit high for something so rare and so unexpected?"
A: "Okay, I see. How about 2.5%? then? Is that rare enough?"
Q: "So the death rate for full-on X26 taser across the chest of this more-susceptible group would be two deaths for each incident?"
A: "Huh? Two?"
Q: "Well, the renormalized death rate is about 5%. So you'd need two-for-one. Or 200% lethal. Right?"
A: "Ah, I see. How about 5% then?"
Q: "So, 100% lethal for each incident then?"
A: "Oh dear - this is not going well..."
Q: "You didn't really think this argument all the way through, did you?" ...

Overall, their argument is quite weak mathematically.