Son of Deep Stops *or* Waiting to be merged with the mother thread...

[shoredivr]

I want to know if the hit rate in that "database" is 5%, 1.6%, something bigger or in between or whatever.

But I already know you don't collect that data and you could never get an institutional review board to approve the collection of medical data from unwitting computer purchasers anyway.

And what information you do collect about outcomes has massive selection bias. If anyone is peddling misinterpreted junk science with no peer review or publication at all here its you.

^this^

From numerous previous posts on threads here and on RBW it seems that Ross is unaware of what selection bias means. Or perhaps he is banking on uneducated divers who don't understand it.

Selection bias - Wikipedia, the free encyclopedia
"Selection bias is the selection of individuals, groups or data for analysis in such a way that proper randomization is not achieved, thereby ensuring that the sample obtained is not representative of the population intended to be analyzed.[1] It is sometimes referred to as the selection effect. The phrase "selection bias" most often refers to the distortion of astatistical analysis, resulting from the method of collecting samples. If the selection bias is not taken into account, then some conclusions of the study may not be accurate."

 

[oya]

It's just great, its the biggest database, the best database.

I wish I had a vast database that showed that I had absolutely everything absolutely right.

Instead of pesky statistical realities.

 

[Storker]

It's just great, its the biggest database, the best database.

 

[rjack321]

I wish I had a vast database that showed that I had absolutely everything absolutely right.

Been right for 20 years!!
Well except for the change to "B"
And that other change to "B/E"

Instead of pesky statistical realities.

Don't look behind that curtain, there's no supporting data here! Don't even need any though, since we got the best reality.

 

[lowviz]

At DEMA last year I sat in on the BW and TO'L presentation on RGBM. Tim started going on about how they had data collected on something like 200,000 dives over 20 years and not one instance of DCS. ...

That is entirely believable if Tim was talking about recreational RGBM. It is monstrously conservative. While being a bubble model, it rejects the gel model of VPM: Reduced gradient bubble model - Wikipedia, the free encyclopedia

 

[cerich]

That is entirely believable if Tim was talking about recreational RGBM. It is monstrously conservative. While being a bubble model, it rejects the gel model of VPM: Reduced gradient bubble model - Wikipedia, the free encyclopedia

not really, even with very conservative profiles among recreational divers there are ALWAYS divers who end up with DCS. It may be a PFO or an uncontrolled assent or something else. The question becomes if there was not any in 200,000 dives how that was possible? Was every case of DCS excluded thru a process of finding out the underlying "cause" of the DCS or was there simply an assumption made that any diver who got DCS while diving RGBM was somehow "at fault" and the record protected.

 

[Storker]

recreational RGBM [...] is monstrously conservative.

Correct me if I'm wrong, but I seem to remember that Suunto's "RGBM" isn't really RGBM, but rather straight Bühlmann with some kind of fudge factor added to make it more conservative for short SIs and fast ascents. Am I totally lost here, or have I got a decent idea of the realities?

 

[rjack321]

not really, even with very conservative profiles among recreational divers there are ALWAYS divers who end up with DCS. It may be a PFO or an uncontrolled assent or something else. The question becomes if there was not any in 200,000 dives how that was possible? Was every case of DCS excluded thru a process of finding out the underlying "cause" of the DCS or was there simply an assumption made that any diver who got DCS while diving RGBM was somehow "at fault" and the record protected.

Exzactly

There "should" be roughly 400 cases of DCS in a 200,000 dive data set even if it's entirely recreational. It might be 150 or 600 cases, but clearly they have some unique screening, selection, or post-processing going on to get "zero".

 

[lowviz]

not really, even with very conservative profiles among recreational divers there are ALWAYS divers who end up with DCS. It may be a PFO or an uncontrolled assent or something else. The question becomes if there was not any in 200,000 dives how that was possible? Was every case of DCS excluded thru a process of finding out the underlying "cause" of the DCS or was there simply an assumption made that any diver who got DCS while diving RGBM was somehow "at fault" and the record protected.

I can't disagree with a word of that.

Nevertheless, I would be happy to post the pure Bruce and Tim recreational RGBM chart that I was given in my course. I'd happily share had it not been liberated by a bunch of Boy Scouts on the Diver II on the Deep 6.

Somebody has that table, please post it here...

 

[cerich]

There has been a lot of statements by Ross to the effect that the scientific community with the exception of some other posters in this thread does not consider VGE as important to DCS and Ross argues VGE means nothing.
Here is some interesting reading...http://www.ntnu.no/documents/10301/340015/Proceedings+of+Validation+of+Dive+Computers+Workshop.pdf

Page 93 is a good discussion on VGE..