Deep Stops Increases DCS

[shoredivr]

I'd argue there is a lot of useful information being posted on decompression.

 

[Dr Simon Mitchell]

Whatever.

...

A useful post is here.

UWSojourner has summed it up for me.

 

[shoredivr]

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A ScubaBoard Staff Message...

Although I am speaking in a moderator voice here, I am not actually moderating. I am just going to explain something related to the moderation of this thread. There have been some reports that have triggered moderator discussion, and I want to write a short treatise on the topic.

Ethos is a legitimate part of the art of persuasive writing and speaking, going back to its origin in classic Greek rhetoric. It supports the argument by either establishing that the speaker has the expertise to make the argument worthy of belief or showing that the opposing speaker is not worthy of belief. There is nothing wrong with that.

Modes of persuasion - Wikipedia, the free encyclopedia
Dr. Williams : USC Upstate : English Program / Ethos-Pathos-Logos-The-3-Rhetorical-Appeals​

A good example occurs with some frequency in the ScubaBoard in the Diving Medicine forum. People will post questions related to dive medicine, and they will get excellent answers from some of the diving physicians we are blessed to have on staff and from other physicians who are not on staff. Unfortunately, they often get incorrect information from unqualified but well-intentioned participants who are repeating something they heard somewhere. How is the reader to know whom to believe? Well, most people will believe the physicians solely because they are physicians. That is a legitimate use of ethos in persuasion.

An ad hominem argument is a fallacious cousin to the legitimate use of ethos. It comes when the attack on the credibility of the user does not have a real value to the argument. For a clear example, let's say that someone was arguing about a certain practice in cave diving, and someone countered by pointing out that the writer had been arrested for selling marijuana in his youth. That would be a clear ad hominem argument, since that previous conviction has nothing to do with the issue or the writer's ability to present an authoritative position.

So there are examples when discussing information about the speaker is obviously important and acceptable. There are cases when it is absolutely not appropriate. Unfortunately, there are many cases that are not so clear and could be argued either way.

The issue of speaker credibility has been raised a number of times in this thread. At times it has been done in ways that are clearly appropriate to the topic. At times, it has been well into the gray area. We have deleted some that were still in the gray area but were sliding in the ad hominem direction. This is a very important discussion, and I hope we can all remember to keep things civil and legitimate.

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I must be in the minority but I found this post useful.

---------- Post added March 7th, 2015 at 08:07 AM ----------

As well, it is not every day that decompression scientists take time to post on a discussion board, so thanks Drs. Mitchell and Doolette. Your efforts are appreciated.

 

[100days-a-year]

Simple answers requested,to the average diver OC or CC in 300' or less doing dives in the 20 to 30 min BTs.Assuming everyone's contentions are true regarding the increased risk of DCS in bubble models deep stops.
What is the risk increase in simple terms?
You are 10% more likely?1%?
Or is it simply minutia not applicable unless extended to ridiculous extremes?

ad hominem attacks in Tech discussions are the norm,so common as to be nearly invisible to me.

 

[igor p]

Correlation of popular diving models with computer profile data and outcomes

Deep stops debate (split from ascent rate thread) - Page 62
In post above BRW (Bruce R. Wienke) was indicating he would be willing to make a statistical validation study of VPM against computer downloaded profiles in LANL Data Bank and in some of my answers I mentioned it is going to happen.
At present time the statistical validation study - correlation to LANL Data Bank is finished and paper released. Same as VPM the USN, ZH-L16 and RGBM models were used in statistical validation study - correlation to LANL Data Bank.
Here is a short quote from document:
"This work provides needed comparisons between global mixed gas diving, specific models, and deep stop data. Our objective is operational diving, not clinical science. The fit of models to data is chi squared significant as follows, using the logarithmic likelihood ratio of null set (actual set) to fit set:
USN – (χ2 = 0.081)
ZHL16 – (χ2 = 0.131)
VPM – (χ2 = 0.717)
RGBM – (χ2 = 0.861)
Submitted – Computers In Biology And Medicine
Pages – 11, Tables – 4, Figures – 0, References – 23
Proofs And Correspondence – B.R. Wienke, LANL MS-D409, Los Alamos, N.M. 87545, (505)
667-1358"
For more info read the paper attached.

Igor P

View attachment model-compare-outcomes_BRW.pdf

 

[100days-a-year]

Thanks for the rapid response Igor.
Hopefully as time goes on we will see bigger sampling sets.I wish my computers and BTs were downloadable.

 

[igor p]

Thanks for the rapid response Igor.
Hopefully as time goes on we will see bigger sampling sets.I wish my computers and BTs were downloadable.

Yes hopefully through time more and more data is collected and sampling sets grow.

Igor P

Sent from my PAP4500DUO using Tapatalk 2

 

[Freewillow]

@igor. read wienke's paper. Correlation versus no correlation. Can you help by explaining what that does imply in practice? Thanks

As far as I read corectly , there is a mixture of Nitrox/Trimix/heliox dives.

One current trend of thought in the french speaking community is that while deep stops are good in Helium mixes, they could be detrimental when one is diving with Nitrogen as the only leading inert gaz. So difficult to draw conclusions on such a mixture. Am I crazy

 

[Dauntless]

Correlation of popular diving models with computer profile data and outcomes

Deep stops debate (split from ascent rate thread) - Page 62
In post above BRW (Bruce R. Wienke) was indicating he would be willing to make a statistical validation study of VPM against computer downloaded profiles in LANL Data Bank and in some of my answers I mentioned it is going to happen.
At present time the statistical validation study - correlation to LANL Data Bank is finished and paper released. Same as VPM the USN, ZH-L16 and RGBM models were used in statistical validation study - correlation to LANL Data Bank.
Here is a short quote from document:
"This work provides needed comparisons between global mixed gas diving, specific models, and deep stop data. Our objective is operational diving, not clinical science. The fit of models to data is chi squared significant as follows, using the logarithmic likelihood ratio of null set (actual set) to fit set:
USN – (χ2 = 0.081)
ZHL16 – (χ2 = 0.131)
VPM – (χ2 = 0.717)
RGBM – (χ2 = 0.861)
Submitted – Computers In Biology And Medicine
Pages – 11, Tables – 4, Figures – 0, References – 23
Proofs And Correspondence – B.R. Wienke, LANL MS-D409, Los Alamos, N.M. 87545, (505)
667-1358"
For more info read the paper attached.

Igor P

View attachment 204298

Applause for this report. As I read it, no model achieved statistical significance, alpha (p)<0.05 by chi sq. Apparently the null hypothesis, no difference in models, stands. Table 4, the data would seem to indicate that there isn't any appreciable difference in 6 stops vs 1 stop i.e. probability for event for 6 stops, nitrox is 0.9% vs. 0.7% 1 step nitrox. The 3 stop probability,1.1%. Was the 2nd line for 6 stop 2nd run of data? if so, no inference that multiple stops have any predictive value for DCS.

Again, great work.

 

[ajduplessis]

P!ssing on the big boys parade..........