Undercurrent--"Why Divers Die"

[in_cavediver]

Statistics, statistics? What the heck is wrong with common sense. Why do you guys try to change the real world to meet your warped idea of reasonable.

The numbers don't have feelings and they don't care what they show. The numbers are the numbers and no one has tried to change them for personal gain in this instance. Accept reality, it is quite liberating.

I have summed my opinions up in a prior message but seeing this made me want to make a few more comments.

Statistics - Statistics are nothing more than mathmatical operations done on a set of numbers to attempt to infer meaning. Statistics in there raw form are factual, accurate and totally meaningless. Humans must look at the results and infer meaning.

For instance, lets say 45% of divers in accidents have a BMI over 30. That means 55% have a BMI under 30. This can be looked at in many ways but none have any bearing. There simply isn't enough information.

Lets add some more information (made up since I have no sourceand no one might). Lets say 65% of the diving population has a BMI over 30. Now, looking at the math, the 'obese' divers are doing much better than the 'skinny' divers. (all things equal, 65% should have been dead, not 45%)

Lets add one more factor. Lets say the total deaths were 100 for the year. Do we yet have enough information - not really. We still need the number of divers and average dives per year with respect to both classes. Only then can we determine if the sample was large enough to yield statistically valid information. To small a sample size, nothing but meaningless noise.

This is also neglecting one whole significant area - independence. Can we show that the conclusion is independent of other factors such as training level, number of prior dives, temperature of the water, depth of dive, dive time prior to accident, Barometric pressure on the surface and the average land speed of an African swallow? - Nope, BMI is not independent of the other factors.

Only once we have the full picture of the data with all dependencies addressed will we have enough to make intelligent inferences. From what I have seen in this thread, that is lacking. Without this data, it's just people looking to advance an opinion based on dubious 'facts'.

 

[Diver Dennis]

Statistics, statistics? What the heck is wrong with common sense. Why do you guys try to change the real world to meet your warped idea of reasonable.

The numbers don't have feelings and they don't care what they show. The numbers are the numbers and no one has tried to change them for personal gain in this instance. Accept reality, it is quite liberating.

How accurate are the numbers? What are the percentages of fit divers diving vs fat divers? How many divers died last year, where the cause can be attributed directly to the shape they were in? There were no numbers at all in your original post, only that "degree of fitness was felt to be central in diving accidents".

I agree that most of us could be in better shape to dive and for better health in general but threads like this exaggerate, IMHO, the danger of diving if you are overweight. I would bet there are more obese or unfit diver that die from heart attacks lugging equipment around topside than actually die from heart attacks in the water. I'm not saying it's OK to be obese but let's put this in perspective.

 

[Charlie59]

If the information were counter-intuitive I could see the point of your discourse, however, this information MAKES SENSE. Please read the articles yourself and direct your questions about issues to the authors.

The bottom line is that if you do anything to exert yourself when unfit or obese you stand an increased likelihood of bad things happening, so why not work on it. This is as important to good diving as good training and skills.

Just because is always an answer, its just not usually right.

Also there are numbers in posts in this thread. 45% of dead divers were overweight and these data are from 2004. Anyone with a DAN membership has access to the data online.

 

[Cacia]

so why not work on it. This is as important to good diving as good training and skills.

you are barking up the wrong tree here.

They will argue with you that "fat is fit" till the cows come home. You will be accused of being arrogant, vain, and of thinking they shouldn't dive.

Actually, I think Rachel hit a major point about the margin of being neutral and the weight issue. The more weight you need, the more likely you will drown when there is a problem, if you ask me.

 

[Diver Dennis]

Also there are numbers in posts in this thread. 45% of dead divers were overweight and these data are from 2004. Anyone with a DAN membership has access to the data online.

How many died as a direct result of being overweight?

I do think a lot of us should be in a lot better shape.

 

[Charlie59]

The statement in the article was that 45% of dead divers were obese while 30% of the general population was obese ( by the >30 bmi). It seems unusual and somehow out of the expected that this degree of obesity is involved in a sport that can be strenuous. How many obese marathoners or tennis players make up the deaths in those sports? Likely less than 45%

It is just a message that could be useful to some. Ignore, if you will, at your own fol-lie.

 

[SparticleBrane]

Just one more thought. If you were a 6’-3” 225 diver suddenly finds themselves in a situation where you need to be towed to shore, 200 yards away, up current in moderate surf, who would you want to get you back? A fit, 105 pound female diver or an overweight, 6’ tall, strong swimmer? (Spare me the “But is she cute?”, comments.)

The best answer is, "whichever has the best rescue technique". I've seen small females tow large males 700-800 yards before so it definitely can be done. It's all about good technique.

 

[Tigerman]

The question IM asking myself first of all is "how many of those obese divers died of a heart attack?"

Next question Id ask myself is "What is the most common cause of death in fatal accidents" Not WHY people fail in doing the right things, but which things. Is it rapid ascents (DCS would be the cod)? Is it not getting up at all (drowning)? Is it o2 hit?

If 60% of all fatal accidents has an element of bouyancy problems, that dont specify if the problem is that people are overweighted or underweighted.
Are we sure we can assume that an obese diver WILL get a larger percentual bouyancy swing?

A math professor once told us in class "statistics is a matter of making the numbers tell the story you want them to tell" and I tend to agree..

 

[MikeFerrara]

A math professor once told us in class "statistics is a matter of making the numbers tell the story you want them to tell" and I tend to agree..

Statistics is calculating probabilities. Then you go on to test the signifcance of those calculations and state things like the error and confidence intervals and so on.

The DAN report doesn't present statistics. It presents the results of counting. It's just raw data. No probabilities are calculated, no significance tests are done...there isn't any statistics about it.

The articles that try to use DAN's counting as statistics to prove their point of the day are useless. Like the article a few years ago that stated the x% of dead divers were found with their weights in place and concluded that the weights were what killed those divers. LOL there are still people running around quoting that stupid article.

I don't even bother reading the DAN report anymore because it never changes. What you see is that amoung non-medical related dive accidents a large percentage of those divers have little training and/or little recent experience and things like buoyancy control and equipment problems come up a lot. skillsYou want to avoid death by disease? Be disease free. You want to avoid diving accidents? Be a skilled diver. Yet the entire industry completely ignores the DAN data and continues to not improve or even LOWER the skill requirements of certification. Divers and insdustry members continue to use those certifications as thought they were indicative of skill level which is demonstrably false.

Sorry folks you're being fed a bunch of sheep dip.

 

[Charlie59]

I wanna learn the skill that keeps you from having a heart attack, now that is skill. Plus, I like sheep dip, especially on strawberries.