DAN national fatality stats

[Ken Kurtis]

I promised in the Catalina fatality stats thread to compile the national numbers and have finally gotten around to that. Shout-thanks to Jeannette Moore at DAN (along with Petar Denoble) for providing some missing info.

Here are the numbers. I'm inserting this as JPG so I can create a chart with columns. Hopefully it displays here. Remember that these represent fatality counts for US & Canadian compressed gas divers (so no freedivers, but would include rebreathers, hookahs, etc.), diving in the US or abroad, and any foreign divers who died while diving in the US. I've grouped things by decade to hopefully factor out some of the statistical anomolies & swings. The DAN folks also caution not to jump to any knee-jerk conclusions about the sudden uptick in the 2007 numbers (although they do seem to stick out like a sore thumb):



One problem here, to state it again, is that we have numerators but no denominators. On the surface (no pun intended), the average fatality rate/year for each decade is going down. But there's no way to really evaluate the significance of that without knowing not only how many divers there are but - more importantly - how many total dives are being made.

If the total number of dives made each year is the same, then the rate is indeed going down. But if we are hypothetically doing half as many total annual dives 2008-2011 as we were doing 1970-1979, the avaerge number/year would have decreased by 34% but the deaths/dive would actually have increased by 32%.

The point is, be careful what conclusions you draw from the numbers.

- Ken

 

[Edward3c]

Hi Ken,

Interesting,

I don't know if its the same in the US as in the UK, but many banks are offering annual travel insurance, including SCUBA, as a perk for banking with them. Taking business away from the few traditional diving insurers.

I suppose I'm asking where does DAN get its raw data from?

Kind regards

 

[Thalassamania]

There are more problems than that Ken. First of all, the earlier numbers (1970 through 1995) includes U.S. Citizens, worldwide combined with anyone who died in U.S. waters. The DAN database is different, I believe. Additionally the collection methods are radically different. The NUADC cases were identified first by a newspaper clipping service or a mailed in form, and then investigated by a researcher, I don't know exactly how DAN collects their data. In any case, there is enough difference in protocols and individual judgements that I do not feel they can be looked at one continuous database, in fact, push come to shove, I'd break the NUADC data up into three separate sets because of changes in the way in which the NUADC operated over the years.

The other "anomalous" peak, in 1978, was (as I recall) in large part training fatalities, and went away when (not necessarily because) PADI disenfranchised their instructors by creating the separate category of "Open Water Instructor."

 

[Ken Kurtis]

I suppose I'm asking where does DAN get its raw data from?

Not sure exactly what their methodology is but I'll send them a note and see if i can get a direct reply to share with everyone.

- Ken

 

[billt4sf]

The average US person has a 300 - 400 times greater chance to be killed DRIVING than DIVING (30,000 driving deaths annually / 88 diving deaths annually).

This is a fairly useless stat -- as Ken points out there are no denominators -- we don't know how many divers there are.

- Bill

 

[Thalassamania]

You don't need denominators, for example: a person in the US (one out of about 300,000,000?) has a 30,000 out of 300,000,000 chance of being killed in a traffic accident, that's 1 in 10,000. If diving were as safe as driving (and let's say for the discussion that there were 100 fatalities per year), then that would imply that the population of divers was on the order of 1,000,000. Do you find that estimate high or low?

 

[Ken Kurtis]

You don't need denominators . . .

Unless you just want to guess, you DO need demoninators. That's what gives us the rate/liklihood/chance etc. Otherwise, all you've got is a raw number.

. . . then that would imply that the population of divers was on the order of 1,000,000. Do you find that estimate high or low?

Personally, I think that number may be high, when you talk about ACTIVE divers. But the number DEMA uses is 2-2.5 million active divers. I was at a presentation by Drew Richardson, PADI prez, and I think he was extrapolating the number of active divers to be closer to 3 million. Or you could trake the financial size of the dive industry (around $700 million annually - but that may not include travel booked but not through a shop or club), figure out what the "average" diver spends a year ($2000 ???) divide that into the total and you'd have an active population of 350,000. Using that as a demoninator instead of 1,000,000 basically triples the chances of dying.

So yes, the denominator matters.

And then you have to define what "ACTIVE" really is. We may be able to say what the number of basic certs issued over a given period has been. But we have NO idea how many of those people keep doiving and we have NO idea of how many dives they do annually. The thought is that most divers do an average of 10-12 dives/year because they do one vacation dive a year, 2 dives per day for 5-6 days. So that gives you a universe of 4.2 million dives producing an average of (using last 4 yrs avg of 80/yr) 80 fatalities a year or 1 fatality per 52,500 dives. Still pretty good odds.

Or you could take Richardson's number of 3 million active divers, assume they do an average of 20 dives/year, giving you a universe of 60 million dives peroducing 80 fatalities per year or 1 fatality per 750,000 dives. REALLY good odds . . . unless you're that one dive.

So again, yes the denominator matters, as do the assumptions you make to arrive at a given conclusion. And therein lies the rub: We have to rely on too many assumptions and if the underlying premise (assumption) is wrong, then the result won't represent an accurate picture of the situation.

- Ken

 

[DandyDon]

That's certainly interesting - thanks!

I believe that DAN tracks accidents & fatalities that are reported to them, but of course will not have anything on those no reported to them - and worldwide, who knows?

Nonetheless, for the population as described, I bet they have reasonably good records. As much as the retail business of the sport keeps growing, I would think it safe to say the number of divers and dives are growing, while the fatality totals are more or less holding. That 2007 spike does stick out.

 

[billt4sf]

Unless you just want to guess, you DO need demoninators. That's what gives us the rate/liklihood/chance etc. Otherwise, all you've got is a raw number.
- Ken

Would it not be possible to require dive shops to report the number of tank fills each year? Don't they get inspected annually or so?

 

[DandyDon]

Would it not be possible to require dive shops to report the number of tank fills each year?

Nope.