Tissue stress associated with bubble formation; potential benefits of diving enriched air

[jhnmdahl]

Spurious Correlation - "A false presumption that two variables are correlated when in reality they are not. Spurious correlation is often a result of a third factor that is not apparent at the time of examination. Spurious comes from the Latin word spurious, which means illegitimate or false."

Nothing to do with the math...

If you get enough legitimate data points with sufficiently high correlation, you can say with increasing certainty that the correlation is real, which is the math. If the correlation is significantly over .5 or so, spurious correlation due to a third factor such as a common divisor can eventually be statistically ruled out. Many times (but not always), you can work through the variables being analyzed to determine whether they are ratios, have a common divisor, etc., so that third/common factors can be statistically removed or better variables can be chosen.

The bigger risk in my mind is that people for the most part know what gas they are diving, and can be predisposed to giving feedback consistent with their expectations. The cost and scope of a significant double-blind study with proper variables would be interesting to me, at least.

 

[Basking Ridge Diver]

If you get enough legitimate data points with sufficiently high correlation, you can say with increasing certainty that the correlation is real, which is the math. If the correlation is significantly over .5 or so, spurious correlation due to a third factor such as a common divisor can eventually be statistically ruled out. Many times (but not always), you can work through the variables being analyzed to determine whether they are ratios, have a common divisor, etc., so that third/common factors can be statistically removed or better variables can be chosen.

The bigger risk in my mind is that people for the most part know what gas they are diving, and can be predisposed to giving feedback consistent with their expectations. The cost and scope of a significant double-blind study with proper variables would be interesting to me, at least.

Wow - is all I can say... ;-)

 

[tursiops]

Wow - is all I can say... ;-)

What is you point? Are you agreeing or disagreeing? "Wow" connotes nothing.

 

[Basking Ridge Diver]

What is you point? Are you agreeing or disagreeing? "Wow" connotes nothing.

Disagree... as in amazement... but did not want to come out and be completely disrespectful - thanks for calling me out... lol

 

[Diver-Drex]

You're not disagreeing with what I have said, so if you want to draw a line between the words correct and fact, so be it. But you continue to disagree with things I haven't said, this confuses me a little. If you're doing this just to illustrate that this is a complex issue that is fine. But really you don't need to make it so difficult.

I have not said Henry's Law explains bubble formation or onset of DCS. I have not discussed bubble mechanics, i.e. the existence of stable micro nuclei, surface tension v tissue pressure, critical radius....

I don't care to discuss those theories and I dont care which one(s) ends up being correct. If I understand the first step in the process and limit inert gas loading up front, I don't have to worry about the various unproven theories on the back end. Henry's Law works just fine that.

I think that is what is important to explain to new divers and it can be explained very simply. It was explained simply to me a long time ago and today what I was told is still correct, accurate, right, true or whatever word other than fact you want insert here.

We don't disagree much, I just prefer I much simpler explanation when possible. I don't need to explain differential calculus and how to derive the acceleration equation to get you to understand that if you fall off a ladder gravity will kick your butt.

 

[dmaziuk]

What is you point? Are you agreeing or disagreeing? "Wow" connotes nothing.

The third factor is rather obvious here: the diver.

There is a group of divers who feel better after breathing nitrox 100% of the time and so the based on that number the third factor can be statistically removed. And thus we can say with increasing certainty that correlation between nitrox and feeling better is real. Very common motif in arguments for existence of god (various), as I recall.

 

[tursiops]

I'm getting a little tired of being told that my feeling better after a Nitrox dive than after an air dive is like religion. Get serious, folks! Firstly, I've provided a quite plausible hypothesis as to why I might feel better. Secondly, YOUR experience of NOT feeling better does not affect MY feeling better! People seem to be trying to argue that "if Tursiops feels better and I do not, that means Tursiops can't possibly be feeling better." The other way the argument is being presented is,. "I don't feel better after a Nitrox dive, so no one does." Yet, there a several of us who are perfectly willing to say that Nitrox works for us, in mitigating fatigue after a dive. Look, I'm a scientist, with several thousand Nitrox and air dives, and I'm an atheist. So don't play that religion card with me! And, take a look at the hypothesis about how Nitrox can work during the off-gassing phase to mitigate sub-clinical DCS. If you want to run controlled studies, take those of us who claim Nitrox benefits for mitigating fatigue, and double-blind us with a bunch of air or Nitrox dives. I'll happily participate.

 

[MaxBottomtime]

This thread reminds me of a joke I heard once. Ask a new diver what causes DCS and he'll say he doesn't know. Ask an instructor on Scubaboard and he'll go on for days about micro bubbles, M-values, tissue stress, etc. Ask a research scientist who has studied DCS at Duke for many years and he'll say he doesn't know.

 

[MaxBottomtime]

I'm getting a little tired of being told that my feeling better after a Nitrox dive than after an air dive is like religion. Get serious, folks! Firstly, I've provided a quite plausible hypothesis as to why I might feel better. Secondly, YOUR experience of NOT feeling better does not affect MY feeling better! People seem to be trying to argue that "if Tursiops feels better and I do not, that means Tursiops can't possibly be feeling better." The other way the argument is being presented is,. "I don't feel better after a Nitrox dive, so no one does." Yet, there a several of us who are perfectly willing to say that Nitrox works for us, in mitigating fatigue after a dive. Look, I'm a scientist, with several thousand Nitrox and air dives, and I'm an atheist. So don't play that religion card with me! And, take a look at the hypothesis about how Nitrox can work during the off-gassing phase to mitigate sub-clinical DCS. If you want to run controlled studies, take those of us who claim Nitrox benefits for mitigating fatigue, and double-blind us with a bunch of air or Nitrox dives. I'll happily participate.

As a scientist, you should be well aware of the placebo effect.

 

[Centrals]

As far as I am concerned Nitrox does nothing to me mentally/physically except extending the bottom time of the dive.