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I do see a tad bit of irony in supporting a PhD candidate's position on the
usefulness of anecdotal data, but what the hell since I agree with it.

I believe that scientific experimentation can yield the most useful
information.  However, many activities involve far too many variables for a
particular experimental conclusion to always be valid under all conditions.
The most valid scientific studies are often developed through the
elimination of as many variables as possible, studying a limited set of
variables or conditions instead.  This is not always possible working in the
field.  How do you think we can actually use computer models to predict
weather? By including every physical variable in real time that we know
affects weather?  Not yet at least.  That is why the National Hurricane
Center runs several models to predict the paths of a huricane which each
emphasize certain and often different aspects of weather phenomenon to
develop a forecast.  Sometimes those models can give ridiculous answers that
the forecasters just discard.  I also believe that knowledge often begins
with anecdotal experiences which in turn may initiate scientific study.
Without knowing enough to ask the question, how can you develop a scientific
study to develop a theory or invalidate an existing one?  

Here's an example (albeit weak but it pertains to diving):

Much of the diving I do involves currents from 0.5mph to 3.5mph and anchor
or fixed point dives.  No big deal.  Do I use a set of tables to determine
whether or not I can pull off an achor dive with 10lbs., 30lbs. or 50lbs. of
camera gear based on prevailing currents?  Of course not!  Have I done tests
in a wind tunnel to determine how much drag different configurations that I
dive with present and how will it affect my swimming performance and
breathing parameters?  Of course not!  Anecdotal evidence and past
experience determines how I accomplish an anchor dive under a particular set
of conditions.  

my $0.02, John

P.S.
Rich, the article on IWR was excellent.  How would you propose to design a
controlled study that would either validate or invalidate some of the
obvious conclusions the existing anecdotal data presented?  Methinks it
would be tough to round up volunteers.  

>> Rich,
>> You're on your anecdotal evidence soap box again.
>> Sorry, it just does not hack it.  Concrete data that provides with the
minimum
>> of conjecture is what we need.  Anecdotal evidence can be downright
misleading.
>> Hey sometimes statistically valid material can be misleading also, but
the former 
>> have more shortcomings.
>
>Of COURSE we need concrete data!  The problem is, we have VERY little of 
>it when it comes to the diving practices were doing.  If we limited 
>ourselves to diving within the bounds of what we know from so-called 
>concrete data, we'd do only air, and maybe nitrox dives in shallow water, 
>would do only heliox dives in deep water, would never do IWR under any 
>circumstances whatsoever, etc. etc.  The point I've been trying to make 
>is that we DON'T HAVE all the concrete data we need! So our options then 
>are:
>
>1) not dive outside the bounds of our existing concrete data;
>2) dive outside the bounds with blinders on and hope for the best;
>3) dive outside the bounds using our collective experience 
>    (= anecdotal evidence) as a guide
>
>Of COURSE anecdodal evidence can be misleading - moreso than "concrete" 
>data - that's why it has to be taken with a grain of salt. But it sure as 
>hell isn't worthless.
>
>Here's an example - oxygen narcosis.
>
>To my knowledge, there has been only one controlled study on the role of 
>oxygen in causing narcosis.  The study was very preliminary, with a 
>restricted sample size, and the very tentative conclusion was that oxygen 
>should be considered about equipotent for narcosis as nityrogen.  My body 
>of anecdotal evidence (personal experiences and discussions with others) 
>is that oxygen seems to be equal to or slightly less narcotic than 
>nitrogen when the PO2 is less than about 1.4; and slightly or 
>considerably more narcotic when the PO2 is more than about 1.7.  I was 
>telling this to Dr. Hugh Greer last week, and he not only found it 
>fascinating, but he'd never heard of that effect before.  He didn't seem 
>to doubt me at all.
>
>So, when I'm diving along with a rebreather at a constant depth and I 
>start to feel increased narcosis do I:
>
>a) Incorporate the anecdotal evidence and check to see if my PO2 is 
>getting to high; or
>
>b) Ignore it because there's no concrete evidence to support the notion 
>that increased PO2 can contribute to narcosis?
>
>I know this is probably not a fair question, but my point is, concrete 
>evedince will only get us so far.  If we want to push beyond the bounds 
>of concrete evidence, we need to take WHATEVER sources of information we 
>have, look at such evidence in the context of what we "know" from the 
>concrete data, and blend it all together using a great deal of 
>intelligence, a handful of salt, and extraordinary prudence.
>
>Aloha,
>Rich
>--
>Send mail for the `techdiver' mailing list to `techdiver@terra.net'.
>Send subscription/archive requests to `techdiver-request@terra.net'.
>
>

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