Is anecdotal evidence dangerous?

[rawls]

Enough with the testimonials

 

[Gene_Hobbs]

Thanks Lynne! We aim to please...

As a scientist, I find the subjective misinterpretation of objective data much more dangerous. Unfortunately, I see those misinterpretations passed along as fact by the media every day.

VERY well said! I have always liked:

Get your facts first, then you can distort them as you please.

and

There are no facts, only interpretations.

This is why both are slides in my talk on diving medical literature.

Someone want to suggest they streamline the process and then make a little online seminar "Getting Started with Project Dive Exploration"? It would certainly help collect more data to supplement the anecdotes.

From the sounds of it, the web submission process (to take care of the issues mentioned above) should be ready for a demo at the DAN Technical Diving Conference in Jan.

 

[Teamcasa]

I forgot who said it I've always liked the quote, "Facts are a very difficult thing." Maybe Twain

 

[The Chairman]

He also said:

There are lies, damn lies and statistics!

Take the Navy Dive Tables: they are a SWAG and should never be considered to be foolproof.

 

[highdesert]

Anecdotal evidence is often the first available in a particular situation. I'm not just referring to diving here. Example ...

A particular plant, common to the tropical regionas of the world, has over 2,000 years of anecdotal evidence pointing to positive treatment of a wide variety of physical ailments. There is litlle, if any, evidence of negatives.

In the late 20th century, there is now a body of science to support the anecdotal evidence. The research relied on groundwork done by analyzing the anecdotes. This is convenient, but prior to that, one would be foolish to totally discredit the anecdotes. In the end, they both have their place.

 

[nereas]

I have bounced to xxx and come back to the surface without a safety stop ... and I was fine. U.S. Navy Standard Air Tables give you 5 at xxx before you were in decompression, that's science ... not anecdote.

Whenever I plug USN data into V-Planner, I get lots longer times than the USN tables require. This makes me truly wonder about the USN tables and not be inclined to try them at all.

That's not telling you anything new, Thal, I am sure.

 

[ClayJar]

Someone want to suggest they streamline the process and then make a little online seminar "Getting Started with Project Dive Exploration"? It would certainly help collect more data to supplement the anecdotes.

From the sounds of it, the web submission process (to take care of the issues mentioned above) should be ready for a demo at the DAN Technical Diving Conference in Jan.

I'll have to remember to keep my eyes open for further developments. I'd certainly love to help, and it'd be a good DM(C) project to help collect data from the divers on our trips once it makes sense and is more streamlined.

 

[Cacia]

I feel that it can be just as dangerous to assume that science will always keep you safe. There are plenty examples of highly skilled divers following scientific, conservative diving practices that still get bent without any obvious reason. Part of the scientific equation involves the use of subjects. Vary the subject...vary the results. Even our own bodys can be different from day to day and that will change how scientific principals apply.

The best approach, IMHO, is to learn your own limitations, slowely and at a safe pace. Strive to do more and to go further with the intent of learning your limitations and not for the reason of breaking records, meeting challenges or impressing others. Use the science as a guide and not a bible and let common sense prevail.

Yes. I like to start with the scientific assumptions and conventional wisdom and tweak it a bit with experience, either my own or someone else's. Operating from only a scientific viewpoint has some pitfalls, one of which is getting on new trends a bit late, or missing an obvious common sense conclusion.

I do sometimes see people who are very smart who cannot really process risk very well.

 

[Kevrumbo]

Cath, that's a fault sometimes attributable to GroupThink. . .

 

[Thalassamania]

Whenever I plug USN data into V-Planner, I get lots longer times than the USN tables require. This makes me truly wonder about the USN tables and not be inclined to try them at all.

That's not telling you anything new, Thal, I am sure.

You're not telling me anything new, but that's all we had from 1956 until the 1980s.

But here's the interesting thing, the recreational community had a horrible record diving U.S. Navy tables while the science community had an excellent one. There have two explanations proposed, and maybe it was a combo:

1. recreational divers did a really poor job of controlling there ascent rates. There were a couple of studies (Egstrom at UCLA, I think) where recreational divers ascent rates were measured whilst the divers were unaware and rates were typically between 100 and 120 fpm! And don't forget that in the early days a diver learned that he or she was low on air by running out. It took discipline and comfort to make a slow ascent whilst breathing through a straw.
2. the U.S. Navy tables were too hard for most people to learn (until NAUI reformatted them circularly) and have way to many "special rules." People just couldn't work them routinely, and this included instructors who rather than demonstrate their stupidity sluffed over them with a lot of hand waving.

I'm interested in anyone's thoughts on the subject.